or (connects at least two alternative words, phrases, clauses, sentences, etc. each of which could make a passage true) / or (connects two equivalent names)

either … or

(logic) inclusive or (connective which yields true when at least one of the predicates is true)

a suffix indicating the third-person singular indicative preterite of a verb in -ar

all-or-nothing

it's all or nothing (something will either be successful or fail catastrophically)

and/or (inclusive "or")

(conjunctive) that is (used to introduce a clarification or explanation)

(logic) xor; exclusive or (logical operation that outputs true only when both inputs differ)

plural of ou exclusivo