In extended use (chiefly with other types of verb), in which fast is characterized as much by its… With reference to sleep: deeply, soundly; so as to…

Solidly, fully, deeply; completely, to the utmost. Obsolete.

to sleep sound, to enjoy deep, unbroken, or undisturbed sleep; to be in a profound sleep.

With reference to sleep, etc.: Deeply, profoundly; without disturbance or interruption.

So as to be difficult to wake; deeply, soundly. Now somewhat rare.

Of physical states or qualities. Profoundly, soundly, with complete absorption of the faculties.

Soundly, roundly; = tightly, adv. 1. Now chiefly in colloquial phrase (good night) sleep tight, a conventional (rhyming) formula used when parting…

Unconscious; (Boxing) defeated through failing to rise within the ten seconds allowed after being knocked down; knocked out. out on one's feet…