The antonym is buy is sell.
Buy is an transitive verb so (nearly always) needs a direct object. e.g. "I bought something". When used ditransitively, the person for whom the direct object is bought can be identified by using a for phrase, e.g. "I bought something for my wife". This can undergo dative shift, e.g. "I bought my wife something."
Buy can be used reflexively, e.g. "I bought something for myself", or "I bought myself something."
- buy in
- i. pay to become part of, usually, a business: He reckons we're going to be really successful and he wants to buy in.
- ii. accumulate, especially stock: There's a strike next week, so we have to make sure we buy in enough stuff to last us till it's over.
- (also reflexive): He bought himself in.
- buy back - retrieve by paying for it:
- buy off - pay to avoid danger:
- buy out - obtain control of a business by buying all the shares:
- buy over - convince someone by paying them:
- buy up - obtain as much as possible: