The same action shifts formality by word choice. In a formal contract, which word for 'get by paying' sounds most formal?

"Purchase" is the most formal word for acquiring something by paying money, which is why it appears in legal contracts, business documents, and official correspondence rather than casual speech. English often has multiple words for the same action sorted by formality level, and legal writing consistently reaches for the most formal option available.

"Buy" is the everyday, neutral term used constantly in ordinary conversation, appropriate almost everywhere but slightly too casual for a formal contract's tone. "Grab" is markedly informal, evoking quick, casual actions like grabbing a coffee, and would sound jarringly out of place in a legal document.

This formality ladder — purchase, buy, grab — repeats across many English verb families (for example, "depart," "leave," "take off"), and choosing the right register is often what separates fluent, professional writing from merely grammatically correct writing.