probably

Probably is an adverb that expresses that something is likely to be the case. It indicates a subjective estimate of probability rather than a statement of certainty. In everyday use, it hedges claims and signals the speaker's level of confidence, as in “She'll probably arrive on time” or “That's probably the best solution.” It can also function as a sentence adverb at the beginning or end of a sentence, as in “Probably, he forgot” or “He will arrive, probably.” In negative form, “probably not” expresses a high likelihood of the opposite.

Grammatical note: It is formed from the adjective probable with the suffix -ly; etymology traces to Latin probabilis through Old French probable. The philosophical or mathematical sense of probability is distinct from everyday hedging; “probably” does not specify a numeric probability unless quantified by context.

Usage guidance: In formal writing, precise probabilities or evidence-based language are preferred; “probably” remains common in reporting, summaries, and informal discourse. It contrasts with “possibly” (lower probability) and “certainly” (high certainty). In some cases, “probably” can be replaced by “likely” or “presumably,” depending on nuance.

See also: related terms include synonyms such as “likely” and “perhaps,” while noting that “perhaps” expresses possibility rather than probability in some contexts.