(nī′tē-nīt′) Informal
Variant of night-night.

[Reduplication of night + -y.]
References in periodicals archive ?
Over to tower, nighty-night don't let the bed bugs bite
Oa schoolgirl called Keira Knightley read bedtime stories to little Dani Dyer, before tucking her in and saying nighty-night.
Laura Numeroff's NIGHTY-NIGHT, COOPER (9780547402055, $16.
This powder is supposed to either send people off to nighty-night, or, in a lower concentration, just make them really, really mellow, and like, not wanna fight, dude.
Who can resist the whimsical packaging and names like Metabolic Frolic, Nighty-Night, Red Zinger and Grandma's Tummy Mint?
SHUSHYBYE is a preschool entertainment and lifestyle brand all about inspiring children to look forward to nighty-night time.