whippersnapper

A whippersnapper is someone who is younger than you are but also irritatingly overconfident and impertinent, like your little smart aleck cousin.

The word whippersnapper describes a specific kind of bratty, know-it-all kid, and it's only used by an older person who is talking about a younger person. It's a fairly old-fashioned word, having been around since the late-1600s, when it apparently arose out of "whip-snapper," which implied a general sense of lots of noise and very little importance. Around the same time, the word "whipperginnie" was a derogatory term for a woman.

Definitions of whippersnapper
1

n someone who is unimportant but cheeky and presumptuous

Synonyms:
jackanapes, lightweight
Type of:
cipher, cypher, nobody, nonentity
a person of no influence

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