What does coincidentally mean?
"Coincidentally" is an adverb describing something that occurs by coincidence — that is, without planning, design, or causal connection between the events involved. It has two closely related uses. First, it describes how an event happens: if two friends meet at a distant airport without having arranged it, they have met coincidentally. Second, and very commonly, it opens a sentence as a discourse marker meaning "as it happens" or "strikingly enough," drawing attention to an unexpected overlap: "Coincidentally, my dentist and my plumber live on the same street." The word carries a neutral to mildly intriguing connotation; it signals surprise at an alignment of circumstances rather than any suspicion or causation. It should not be confused with "incidentally," which merely introduces a side remark. Derived from the Latin incidere, "to fall upon," it belongs to the same family as "coincide" and "coincidence."
adverbIn a way that happens by coincidence, without being planned or arranged. Also used to introduce a fact that is strikingly or amusingly coincident with something else.
- By chance; as a result of coincidence, without deliberate arrangement.
- Used to introduce a remark about a striking or notable coincidence: 'it just so happens that...'
"Coincidentally, she had booked the same flight as her old college roommate."
"Coincidentally, the two scientists published nearly identical findings within the same week."
"Quite coincidentally, the stranger sitting next to me turned out to be my new neighbour."
The word hides a little mathematical surprise: its Latin root incidere means 'to fall upon' — so a coincidence is literally two things falling on the same spot.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of coincidentally
"Coincidentally" derives from the verb "coincide," formed from the Latin prefix co- ("together") and incidere ("to fall upon" or "to happen"), from in- plus cadere ("to fall"). The adjective "coincidental" and adverb "coincidentally" developed in English alongside "coincidence," which entered the language around the early modern period to describe events occupying the same time or space. Cognate forms appear across European languages that borrowed the same Latin root, such as French coïncider and Spanish coincidir.
Related word forms
How coincidentally is actually used
Neutral in register and suitable for both formal and informal contexts. In sentence-initial position it often functions as a discourse marker meaning 'as it happens,' softening what might otherwise sound like an implausible claim of connection between events.
Easily confused with coincidentally
"Coincidentally" means by coincidence or chance overlap, while "incidentally" means "by the way," introducing a remark aside from the main point.