/bās/
Noun, pl. bases
1. (Science: chemistry)
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. A substance that can accept hydrogen cations (protons) or more generally, donate a pair of valence electrons. (wikipedia.org)
3. (Anatomy)
The part of an organ nearest its point of attachment) “the base of the skull.” (wordnetweb.princeton.edu)
4. (Nucleotide, base)
A phosphoric ester of a nucleoside; the basic structural unit of nucleic acids (DNA or RNA). (wordnetweb.princeton.edu)
5. A purine or pyrimidine group in a nucleotide or nucleic acid. (Google Dictionary)