The nonacid part of a salt, a substance that combines with acids to form salts, a substance that dissociates to give hydroxide ions in aqueous solutions, a substance whose molecule or ion can combine with a proton (hydrogen ion), a substance capable of donating a pair of electrons (to an acid) for the formation of a coordinate covalent bond. (biology-online.org)
2. Base of the heart, a portion of the heart opposite the apex of the heart. (wikipedia.org)
3. (Botany, Zoology)
a. The part of an organ nearest its point of attachment.
b. The point of attachment.