Proof: An answer reached through valid formal logic (for example maths or deduction). Not to be confused with evidence.
Prove: The act of providing proof, not to be confused with giving evidence.

Valid logic: When logic applied follows the agreed upon (and generally formal) rules of logic (All apples are made of meat. I ate an apple, therefore I ate meat).
Sound logic: When logic applied uses premises supported by known facts. (Apples are not made of meat. I ate only an apple, therefore I did not eat meat).
Premise: Statements taken to be true. If people disagree with your premise, your logic (if correctly applied) is valid to them, but not sound.
Assertion: Statements claimed to be true. In logic when you claim that your premise is true.
Truth: In accord with fact or a given standard. A topic so hotly contested that a more precise definition is near impossible to give.

Deduction / deductive reasoning: A form of logic where if the premise is true then the conclusion is necessarily true (Apples are green, therefore the apple is green).
Induction / inductive reasoning: A form of logic where the premises support that the conclusion is true (All apples I have seen are green, therefore apples are green).
Abduction / abductive reasoning: A form of logic where you find the theory from the observation (He claims an apple must be green, therefore he has only seen green apples).
Inference: To move from premise to conclusion, through deduction, induction or abduction.

Science: Search for knowledge, generally refers to the collective of academia dedicated to such a search.
Empirical science: Science based on sensory observation / measurement. Almost always points to such science using falsification of hypotheses as method.
Hypothesis: Something seen as true for the purpose of testing it. In empirical science it generally means something you will attempt to falsify. (Our research predicts the planet’s orbit will look like this)
Falsification: An attempt to disprove a hypothesis, if falsification fails the hypothesis is supported but if it succeeds the hypothesis is wrong (The planet’s orbit was not as predicted)
Ad-hoc hypothesis: Supporting hypothesis used to hold up a falsified hypothesis (There is a moon influencing the planet’s orbit).
Theory: In science it means a hypothesis that is strongly supported, outside science it means an idea / guess.
Correlation: That two phenomena are somehow statistically related (Ice-cream consumption and drownings increase and decrease proportionally).
Causality: That one thing directly leads to another (More people went swimming because it was summer).

Evidence: Information that supports an assertion / conclusion.
Evident: When evidence itself makes a conclusion almost foregone.
Facts: Something that has happened or is correct and can be demonstrated.
Cite / citation: A reference to a credible source / expert.

Belief: Believing something to be actual, it does not speak to the strength of evidence , only the conviction.
Faith: Trust in someone or something, often points to a sense of obligation towards this someone or something.

Rational: Formally that something is based on reason, informally that something is generally supported.
Empirical: Based on sense experience, in science points to the use of measurements that can be observed.
Bias: Holding a particular perspective, often used negatively as in refusing to let go of that perspective.
Subjective: Something only true to an individual or group of individuals.
Objective: In philosophy that something is true even outside observation / bias. In science it generally means research that takes reasonable measures to be as unbiased as possible.
Paradigm: The generally accepted practices in an academic, scientific or philosophical field.
School: A set of ideas attributed to certain group of individuals, often used more informally than paradigm.

Theism: Belief in god, by some taken to only to mean belief in an interfering God.
Deism: Belief in a non-interfering God and the rejection of revelation. By some seen as a sub-set of theism.
Atheism: Lack of belief in gods or disbelief in gods.
Strong atheism: Atheists who explicitly assert that "there are no gods" .
Weak atheists: Atheists who do not explicitly assert that "there are no gods".
Agnostic: Someone who asserts that the existence of God is not knowable.

Personal God: A god that exhibits some type of personal traits, a god you can know.
Revelation: Testament, written or spoken, that is seen as legitimate reasons to believe in a religion.
Abrahamic religion: Religions that incorporate the story of Abraham. Generally means Judaism, Christianity and Islam.
Religion: A collective belief in some greater goal for humankind, typically involves belief in the supernatural and adherence to certain rituals.
Spirituality: Originally it meant religious reshaping of yourself. Now typically points to personal quest for deeper meaning, often with supernatural elements.
Irreligiosity: The rejection of religion, it does not on its own explicitly say if you are an atheist or theist, but it is generally perceived to be more common in atheists and often seen as an attribute of new atheism.
Religiosity: How someone adheres to religion, in a narrow sense it can mean a scale of how religious a person is.
New atheism: A collective term for a cultural movement of atheists (whether explicitly organized or not) that more aggressively rejects theism and religion.

Method: In science it means techniques for finding knowledge, the practical application of methodology. "How you do this type of science".
Methodology: Theoretical assessment of principles within a scientific discipline. "Why you do this science this way".
Exegesis: Interpretation of holy texts, typically the Bible
Hermeneutics: These days typically taken to mean using literal readings of texts and interpreting those from a context / historical point of view, then returning to the work and see if it fits. Originally stems from theological practices, now also used in arts and humanities.

Epistemology: The philosophical study of knowledge.
Ontology: The philosophical study of existence and reality.
Teleology: The philosophical study of the purpose of things.
Ontological argument: The argument that God exists because we can conceive of God.
Teleological argument: The argument that God exists because of how the world is / is designed.
Cosmological argument: The argument that can God's existence be inferred from facts, typically that this is evident from causal events ("the first mover").

Intrinsic: A trait or purpose belonging to the thing itself (The violin is made of wood).
Extrinsic: A trait or purpose given to the thing (The violin is made to be played).

Rationalism: The philosophical view that reason is the prime source of knowledge (Descartes / Spinoza)
Empiricism: The philosophical view that experience is the prime source of knowledge (Hume / Popper)
Idealism: The philosophical view that reality is mind-dependent, we can only know objects based on the observations we do of them. (Kant / Schopenhauer)
Phenomenology: The philosophical idea that you can only understand the world through individual experience of phenomena (Husserl / Heidegger).
Solipsism: The philosophical idea that only one’s own mind is sure to exist (Berkeley / Descartes)
Philosophical realism: The idea that reality exist independently of observers (Plato)
Scientific realism: The view that science describes the real world (Richard Boyd / Putnam).
Existentialism: The philosophical idea that existence precedes essence, you are an individual therefore things have essence (Kierkegaard / Sartre)
Nihilism: The idea that that all values are baseless and that nothing can be known. If it is often mistaken for related theories that incorporate nihilism (moral nihilism, existential nihilism, radical skepticism). Generally attributed to Nietzsche, who dedicated much of his philosophical work to warn against nihilism.

I figured a small dictionary of typical RGT terms could be useful, mostly an exercise to re-examine some things for myself, but perhaps it could also have some utility here.

Feel free to offer criticism.

Thank you for taking the time for doing this.

Agnostic has two meanings. In addition to the one you provided it also describes someone that states "I personally do not know if there is a God" whithout making any claims whether god is knowable.

Thx for writing this up.

Science: Search for knowledge understanding...

Or is that too pedantic?

Scientism is a useful addition among the other isms.

http://www.philosophybasics.com/branch_scientism.html

https://www.aaas.org/page/what-scientism

Good job TD! I would suggest Transcendentalism to be included. By the way, as a dictionary, wouldn't have been better if the terms were arranged alphabetically?

That could be, I would say that such a definition is an informal one though. I think that distinction is important, since agnosticism as a term has a history as mainly an intellectual position.

Agnostic: Formally someone who asserts that the existence of God is not knowable. Informally can be used describe someone who is not committed to believing in either the existence or the nonexistence of god(s)".

I wouldn't say pedantic, given that "to know" doesn't necessarily convey understanding in everyday use. I.e. in everyday parlor there isn't a necessarily a conflict between a person "knowing that someone is president" and that person not understanding what it means (like say, a child).

Adding knowledge seems like the natural thing to do:
Knowledge - In science and philosophy typically taken to mean statements that are justified and believed. Typically such statements are taken be true or closely aligned with the truth.

Yeah, that is a good suggestion.

Scientism - To view science as the superior source of knowledge and other approaches as inferior, mainly used as a negative term to describe people putting too much stock in science.

I tried that and decided to try to put them in sections that fit together (which is not perfect either, since some belong in more categories). Perhaps alphabetically would have been better.

I will try to define transcendentalism, but it is a view on life that often tends to oppose strict definitions.

Transcendentalism - An amalgamation of several philosophical and religious influences. Transcendentalists maintain that a relationship with the universe is and should be individual and subjective (Waldo Emerson / Thoreau)