Other forms: required, requires, requiring
To require something is to need it, said in the voice of rules and forms. The job requires a driving licence, the recipe requires three eggs, visitors are required to sign in at the desk.
Because it belongs to regulations and instructions, require turns up most in the passive: you are required to, applicants are required to, a ticket is required. It also means to demand with authority behind you — the court required him to hand over the documents. The noun is requirement (entry requirements, a legal requirement), and requisite is the stiff adjective beside it. Keep it apart from request: you request a favour, you require a passport. "If required" is a handy tail to hang on the end of a sentence: bring a jacket, if required.
1verbrequireTo need something for a particular purpose or as a condition.
“The recipe requires three eggs and a little cold water.”
2verbdemandTo order officially that someone do something.
“Passengers are required to show a ticket before boarding.”
formal in this meaning — an editor’s judgement
Too few real examples of this word to estimate which sense is commonest.
Latin requīrō meant to seek, to ask for, to require — literally "to seek back", from re- ("back, again") and quaerō ("to seek"). Old French turned it into requerre, and English took it from there. The formality it still carries is the formality of someone asking on behalf of a rule.
Latin
requīrō — to require, seek, ask for
Old French
requerre
English, today
require
Built from
From Old French requerre (whence Modern French requérir), from Latin requīrō (“to require, seek, ask for”) literally “to seek back”, from re- (“back; again”) + quaerō (“to seek”).
Etymology from Wiktionary, CC BY-SA