tuck in

tuck in

1. To fold or gather something, typically a fabric, and push it under or into something else. A noun or pronoun can be used between "tuck" and "in." Would you tuck the sheets in, please? You should tuck in your shirt, or you'll look like a slob for your interview.
2. To place something inside of something else, typically something small, in order to secure it. In this usage, a noun or pronoun is used between "tuck" and "in." She tucked the money in an envelope and slipped it under the door. I tucked your glasses in the side pocket of your jacket.
3. To contract or pull in something, such as a body part. A noun or pronoun can be used between "tuck" and "in." Be sure to tuck in your arms and legs after you jump off the diving board. You'll have to tuck your arms in to squeeze through.
4. To place someone, typically a child, in bed and ready them for sleep, often by actually tucking the bedsheets around them. A noun or pronoun can be used between "tuck" and "in." Do you want me or Mommy to tuck you in tonight? I Just tucked in the kids, so we have the rest of the night to ourselves.
5. To begin eating. Often used as an imperative. OK, tuck in before the food gets cold! The hungry child tucked in as soon as the food was in front of him.
See also: tuck
Farlex Dictionary of Idioms.

tuck someone in(to) something

 and tuck someone in
to place someone into something carefully; to wrap someone in blankets or something similar. Father tucked Jimmy into bed an hour later than he should have. Please tuck in Jimmy.
See also: tuck

tuck something in (to) something

 and tuck something in
to fold or stuff something into something. Please tuck your shirttail into your pants. Tuck in your shirt tail. When you make the bed, you have to tuck the sheets in.
See also: tuck
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

tuck in

Thrust in the edge of or end of something, such as bed linens or a shirt; also, make a child secure in bed by folding in the bedclothes. For example, Tuck in your shirt; it looks awful hanging out of your pants, or Mother went upstairs to tuck in the children. [First half of 1600s]
See also: tuck
The American Heritage® Dictionary of Idioms by Christine Ammer.

tuck in

v.
1. To gather something up and fold, thrust, or turn in so as to secure or confine it: The teacher told the boys to tuck in their shirts. I threw the sheet over the bed and tucked it in at the corners.
2. To make someone secure in bed for sleep, especially by tucking bedclothes into the bed: I tucked in my daughter and said good night. The babysitter tucked the little boy in.
3. To draw in some body part; contract something: She tucked in her arms and shook her head. The turtle tucked in its head.
4. Slang To begin to eat heartily: Dinner was served, and we tucked in.
See also: tuck
The American Heritage® Dictionary of Phrasal Verbs.
See also:
  • add in
  • all right
  • a/the feel of (something)
  • (I) wouldn't (do something) if I were you
  • a straw will show which way the wind blows
  • a crack at (someone or something)
  • (you) wanna make something of it?
  • all for the best
  • a thing of the past
  • a slew of (something)