The Collaborative International Dictionary of English v.0.48:
Cover \Cov"er\ (k?v"?r), n.
1. Anything which is laid, set, or spread, upon, about, or
over, another thing; an envelope; a lid; as, the cover of
2. Anything which veils or conceals; a screen; disguise; a
cloak. "Under cover of the night." -- Macaulay.
A handsome cover for imperfections. --Collier.
3. Shelter; protection; as, the troops fought under cover of
the batteries; the woods afforded a good cover.
Being compelled to lodge in the field . . . whilst
his army was under cover, they might be forced to
4. (Hunting) The woods, underbrush, etc., which shelter and
conceal game; covert; as, to beat a cover; to ride to
5. That portion of a slate, tile, or shingle, which is hidden
by the overlap of the course above. --Knight.
6. (Steam Engine) The lap of a slide valve.
7. [Cf. F. couvert.] A tablecloth, and the other table
furniture; esp., the table furniture for the use of one
person at a meal; as, covers were laid for fifty guests.
To break cover, to start from a covert or lair; -- said of
Under cover, in an envelope, or within a letter; -- said of
a written message.
Letters . . . dispatched under cover to her