Definify.com

Webster 1913 Edition

Verb.

[1st pref.

un-

tuck

To unfold or undo, as a tuck; to release from a tuck or fold.

untuck ‎(third-person singular simple present untucks, present participle untucking, simple past and past participle untucked)

To remove something from a relatively hidden location or position.

As soon as work is over, I'm going to untuck this shirt and take off my shoes.

The cat will wake up in a tightly curled position, then untuck her head, and gradually her limbs, and then stretch.