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DECIDE, DETERMINE, SETTLE, RULE, RESOLVE mean to come or cause to come to a conclusion.

DECIDE implies previous consideration of a matter causing doubt, wavering, debate, or controversy.

e.g. she decided to sell her house

DETERMINE implies fixing the identity, character, scope, or direction of something.

e.g. determined the cause of the problem

SETTLE implies a decision reached by someone with power to end all dispute or uncertainty.

e.g. the dean's decision settled the campus alcohol policy

RULE implies a determination by judicial or administrative authority.

e.g. the judge ruled that the evidence was inadmissible

RESOLVE implies an expressed or clear decision or determination to do or refrain from doing something.

e.g. he resolved to quit smoking

DISCOVER, ASCERTAIN, DETERMINE, UNEARTH, LEARN mean to find out what one did not previously know.

DISCOVER may apply to something requiring exploration or investigation or to a chance encounter.

e.g. discovered the source of the river

ASCERTAIN implies effort to find the facts or the truth proceeding from awareness of ignorance or uncertainty.

e.g. attempts to ascertain the population of the region

DETERMINE emphasizes the intent to establish the facts definitely or precisely.

e.g. unable to determine the origin of the word

UNEARTH implies bringing to light something forgotten or hidden.

e.g. unearth old records

LEARN may imply acquiring knowledge with little effort or conscious intention (as by simply being told) or it may imply study and practice.

e.g. I learned her name only today learning Greek

verb with object

1. cause (something) to occur in a particular way; be the decisive factor in:

〈物･事が〉〈物･事〉を左右する, 決定する (!しばしば受け身で)

e.g. it will be her mental attitude that determines her future.

2. ascertain or establish exactly, typically as a result of research or calculation:

〖determine (that)節/wh節〗 …ということを, …かを突き止める, 確認する, 見極める

e.g. with clause : the point of our study was to determine what is true, not what is practicable

〈人などが〉(観察･推論により)〈事実･真実など〉を特定する, 明らかにする

e.g. officials are working with state police to determine the cause of a deadly bus crash.

Mathematics specify the value, position, or form of (a mathematical or geometric object) uniquely.

〘数〙 …の位置, 形を決定する

3. no object firmly decide:

«…を» 決心する(decide) «on» ; 決定, 特定する

e.g. he determined on a withdrawal of his forces

e.g. with infinitive : she determined to tackle Stephen the next day.

4. Law, archaic bring or come to an end.

〘法〙 〈訴訟など〉を終結する

late Middle English: from Old French determiner, from Latin determinare ‘limit, fix’, from de- ‘completely’ + terminare ‘terminate’.