From The Collaborative International Dictionary of English v.0.48:
Runt \Runt\, n. [Written also rant.] [Scot. runt an old cow,
an old, withered woman, a hardened stem or stalk, the trunk
of a tree; cf. D. rund a bullock, an ox or cow, G. rind. Cf.
Rother, a.]
1. (Zool.) Any animal which is unusually small, as compared
with others of its kind; -- applied particularly to
domestic animals.
[1913 Webster]
2. (Zool.) A variety of domestic pigeon, related to the barb
and carrier.
[1913 Webster]
3. A dwarf; also, a mean, despicable, boorish person; -- used
opprobriously.
[1913 Webster]
Before I buy a bargain of such runts,
I'll buy a college for bears, and live among 'em.
--Beau. & Fl.
[1913 Webster]
4. The dead stump of a tree; also, the stem of a plant. [Obs.
or Prov. Eng.] --Halliwell.
[1913 Webster]
Neither young poles nor old runts are durable.
--Holland.
[1913 Webster]