cleft

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Divided; split.
• adjective Botany Having indentations that extend about halfway to the center, as in certain leaves.
• noun A crack, crevice, or split.
• noun A split or indentation between two parts, as of the chin.

from The Century Dictionary.

• noun A space or opening made by cleavage; a crevice; a fissure; a furrow; a rift; a chink.
• noun . The point where the legs are joined to the body; the crotch.
• noun 3. That which is cloven; a cloven hoof.
• noun A disease of horses characterized by a crack on the bend of the pastern.
• noun A piece made by splitting: as, a cleft of wood.
• noun Preterit and past participle of cleave.
• Split; divided; cloven.
• In botany, divided half-way down or somewhat further, with narrow or acute sinuses between the lobes: applied to a lobed leaf, calyx, etc.

from the GNU version of the Collaborative International Dictionary of English.

• imp. & p. p. from cleave.
• adjective Divided; split; partly divided or split.
• adjective (Bot.) Incised nearly to the midrib.
• noun A space or opening made by splitting; a crack; a crevice.
• noun A piece made by splitting.
• noun (Far.) A disease in horses; a crack on the band of the pastern.
• noun See under Branchial.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An opening, fissure, or V-shaped indentation made by or as if by splitting.
• noun A piece made by splitting.
• noun A disease of horses; a crack on the band of the pastern.
• verb Simple past tense and past participle of cleave.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a split or indentation in something (as the palate or chin)
• adjective having one or more incisions reaching nearly to the midrib
• noun a long narrow opening