What does dilated mean?
"Dilated" is the adjective form of the verb "to dilate," meaning to become wider, larger, or more open. Its most familiar use is medical and physiological: pupils dilate in low light or under the influence of certain drugs, blood vessels dilate to increase blood flow, and the cervix dilates during childbirth. In these contexts the word is precise and clinical, carrying no emotional charge. Less commonly, "dilated" can describe speech or writing that has been stretched out at unnecessary length, as in a "dilated account" of events — a usage inherited from older rhetorical tradition and now largely confined to formal or literary prose. The word derives from the Latin "dilatare," formed from "dis-" (apart) and "latus" (wide), literally meaning "to spread wide." Because dilation is often involuntary — a response to light, emotion, medication, or exertion — the word frequently appears in contexts of diagnosis, observation, and bodily change, making it essential vocabulary in medicine, optometry, and obstetrics.
Widened or expanded beyond normal size, especially of a bodily opening, organ, or passage.
"The optometrist examined her dilated pupils under bright light."
Most common in medical contexts.
(Of speech or writing) expanded or elaborated at length.
"His dilated explanation of the rules bored everyone at the meeting."
Literary and somewhat archaic.
Your pupils dilate when you look at someone you're attracted to — a reaction so reliable it was once used as a lie-detector test in Renaissance Italy.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dilated
"Dilated" comes from the Latin "dilatare," meaning "to spread wide" or "enlarge," itself built from "dis-" (apart) plus "latus" (broad, wide). The word passed into English via French in the late Middle English period, with medical and anatomical uses well established by the early modern era. It shares its root with "latitude," which also descends from "latus," preserving the original sense of breadth.
Related word forms
How dilated is actually used
Primarily a technical or medical term when applied to physical structures such as pupils, cervixes during labor, blood vessels, or the heart. The figurative sense describing lengthy, elaborate discourse is literary and somewhat dated. In everyday conversation, people more often say "wide" than "dilated."
Easily confused with dilated
"Delated" means accused or informed against (from Latin delatare), while "dilated" means widened or expanded.