random
adj.adj. happening or chosen by chance rather than according to a plan. In casual conversation, you might use it to describe something unexpected or strange.
adj. governed by or involving equal chances for each item or outcome; lacking a definite plan, purpose, or pattern. In informal registers, it functions as a descriptor for the unexpected, peculiar, or socially incongruous.
The computer picks a random winner from the list.
The researchers used a random sample of participants to ensure the study results were not biased.
While the distribution of stars might appear random to the naked eye, astronomical mapping reveals complex gravitational structures that dictate their relative positions over billions of years.
From earlier randon, from Middle English randoun, raundon, from Old French randon, from randir (“to run, gallop”) (whence French randonnée (“long walk, hike”)), from Frankish randiju (“a run, race”) or Old Norse rend (“a run, race”), both from Proto-Germanic randijō, from rinnaną (“run”, verb), from Proto-Indo-European (H)r̥-nw- (“to flow, move, run”). Cognate with Middle Low German uprinden (“to jump up”), Danish rende (“to run”). See run.
Typically precedes the noun it modifies. In informal speech, it can function as a predicative adjective to describe a person or event as weird or out of place.
at the randomat randomWhen used as part of a prepositional phrase meaning 'without a plan', the word functions as a noun and does not take an article.