Bite-one-s-lip

either of the two fleshy parts or folds forming the margins of the mouth and functioning in speech.
Usually, lips. these parts as organs of speech:
I heard it from his own lips.
a projecting edge on a container or other hollow object:
the lip of a pitcher.
a liplike part or structure, especially of anatomy.
any edge or rim.
the edge of an opening or cavity, as of a canyon or a wound:
the lip of the crater.
Slang. impudent talk; back talk:
Don’t give me any of your lip.
Botany. either of the two parts into which the corolla or calyx of certain plants, especially of the mint family, is divided.
Zoology.

a labium.
the outer or the inner margin of the aperture of a gastropod’s shell.

Music. the position and arrangement of lips and tongue in playing a wind instrument; embouchure.
the cutting edge of a tool.
the blade, at the end of an auger, which cuts the chip after it has been circumscribed by the spur.
(in a twist drill) the cutting edge at the bottom of each flute.
of or relating to the lips or a lip:
lip ointment.
characterized by or made with the lips:
to read lip movements.
superficial or insincere:
to offer lip praise.
to touch with the lips.
Golf. to hit the ball over the rim of (the hole).
to utter, especially softly.
to kiss.
to use the lips in playing a musical wind instrument.
lip off, Slang. to talk impudently or belligerently.
bite one’s lip / tongue, to repress one’s anger or other emotions:
He wanted to return the insult, but bit his lip.
button one’s lip, Slang. to keep silent, especially, to refrain from revealing information:
They told him to button his lip if he didn’t want trouble.
Also, button up.
hang on the lips of, to listen to very attentively:
The members of the club hung on the lips of the visiting lecturer.
keep a stiff upper lip,

to face misfortune bravely and resolutely:
Throughout the crisis they kept a stiff upper lip.
to suppress the display of any emotion.

smack one’s lips, to indicate one’s keen enjoyment or pleasurable anticipation of:
We smacked our lips over the delicious meal.
noun
(anatomy)

either of the two fleshy folds surrounding the mouth, playing an important role in the production of speech sounds, retaining food in the mouth, etc related adjective labial
(as modifier): lip salve

the corresponding part in animals, esp mammals
any structure resembling a lip, such as the rim of a crater, the margin of a gastropod shell, etc
a nontechnical word for labium, labellum (sense 1)
(slang) impudent talk or backchat
the embouchure and control in the lips needed to blow wind and brass instruments
bite one’s lip

to stifle one’s feelings
to be annoyed or irritated

(slang) button one’s lip, button up one’s lip, to stop talking: often imperative
keep a stiff upper lip, to maintain one’s courage or composure during a time of trouble without giving way to or revealing one’s emotions
lick one’s lips, smack one’s lips, to anticipate or recall something with glee or relish
verb lips, lipping, lipped
(transitive) to touch with the lip or lips
(transitive) to form or be a lip or lips for
(transitive) (rare) to murmur or whisper
(intransitive) to use the lips in playing a wind instrument
n.
v.

Insolent, impertinent, or presumptuous talk; sass, sauce: I don’t want none of your lip (1821+)
A lawyer; mouthpiece (1929+ Underworld)

In addition to the idioms beginning with lip
lip service