(intransitive, idiomatic) to maintain a background awareness of something; to remain alert to changes without it occupying one's full attention.

(medicine) A congenital muscular dystrophy associated with severe myopia or glaucoma and mental retardation or hydrocephalus

(idiomatic) Hyperbole to illustrate something that is almost impossible to do or to make happen.

(idiomatic) To maintain one's concentration fixed on one important theme.

(of a look or glance) Sideways, obliquely, askance / (of a look or glance) With suspicion.

To sacrifice something valuable.

A good-natured toast used when drinking an alcoholic beverage.

(idiomatic, colloquial, humorous) A notional look of anticipation or hope (either for sex or a child) in one's father's eyes at or around the time of one's conception.

(idiomatic) More than is apparent or readily noticeable.

(figuratively) To remain vigilant at all times, especially by remaining partially awake or sleeping only lightly so as to avoid being caught off guard.