intransitive. To make a binding promise, typically while linking one’s little finger with that of another person (see pinkie swear n.). Frequently used elliptically, esp. when giving or seeking reassurance that a promise will be kept. Also transitive: to swear (something) in this manner. Cf. pinkie promise v.Esp. in the language of children and young teenagers.When used by or with reference to adults, often carrying negative or sarcastic connotations, implying that childish oaths are made and broken easily, or that the promise in question is made lightly, glibly, or without the intention of honouring it.

A promise made while linking one’s little finger with that of another person, and regarded as especially binding or sincere. Hence more generally (without the linking of fingers): a binding or sincere promise (see note). Cf. pinkie promise n.Esp. in the language of children and young teenagers.When used by or with reference to adults, often carrying negative or sarcastic connotations, implying that childish oaths are made and broken easily, or that the promise in question is made lightly, glibly, or without the intention of honouring it.