Busy, a.
Etymology: [OE. busi, bisi, AS. bysig; akin to D. bezig, LG. besig; cf. Skr. bh to be active, busy.]
1. Engaged in some business; hard at work (either habitually or only for the time being); occupied with serious affairs; not idle nor at leisure; as, a busy merchant. Sir, my mistress sends you word THat she is busy, and she can not come. Shak.
2. Constantly at work; diligent; active. Busy hammers closing rivets up. Shak. Religious motives . . . are so busy in the heart. Addison.
3. Crowded with business or activities; -- said of places and times; as, a busy street. To-morrow is a busy day. Shak.
4. Officious; meddling; foolish active. On meddling monkey, or on busy ape. Shak.
2 more senses
5. Careful; anxious. [Obs.] Chaucer.
Syn. -- Diligent; industrious; assiduous; active; occupied; engaged.
1 other Webster entry under this spelling
Busy, v. t. [imp. & p. p. Busied; p. pr. & vb. n. Busying.]
To make or keep busy; to employ; to engage or keep engaged; to occupy; as, to busy one's self with books. Be it thy course to busy giddy minds With foreign quarrels. Shak.
Shades of meaning
Fernald has no entry of its own for busy; he lists it under active, industrious.
Where he writes about it:
Active refers to both quickness and constancy of action; in the former sense it is allied with agile, alert, brisk, etc.; in the latter, with busy, diligent, industrious. — from active
The active love employment, the busy are actually employed, the diligent and the industrious are habitually busy. — from active
Busy applies to an activity which may be temporary, industrious to a habit of life. — from industrious
We say a man is busy just now; that is, occupied at the moment with something that takes his full attention. — from industrious
But busy can be used in the sense of industrious, as when we say he is a busy man. — from industrious