The Collaborative International Dictionary
Twain cloud
Twain \Twain\, a. & n. [OE. twein, tweien, tweyne, AS.
tw[=e]gen, masc. See Two.]
Two; -- nearly obsolete in common discourse, but used in
poetry and burlesque. ``Children twain.''
--Chaucer.
And whosoever shall compel thee to go a mile, go with
him twain.
--Matt. v. 41.
In twain, in halves; into two parts; asunder.
When old winder split the rocks in twain.
--Dryden.
Twain cloud. (Meteor.) Same as Cumulo-stratus.
Wiktionary
twain cloud
n. (context meteorology English) stratocumulus