Looking quickly or secretly at something, usually hiding part of your face or body so you won't be noticed.
Possibly from Scandinavian languages (Old Norse), related to 'peak.' The meaning 'to look slyly' developed in the 1500s and differs from 'peaking' (reaching a maximum).
English has a hidden spelling trap: 'peeking' (looking), 'peaking' (reaching maximum), and 'piquing' (sparking interest) all sound identical but have completely different meanings and origins!
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