'lowercase' definitions:

Definition of 'lowercase'

(from WordNet)
adjective
Relating to small (not capitalized) letters that were kept in the lower half of a compositor's type case; "lowercase letters; a and b and c etc" [ant: uppercase]
noun
The characters that were once kept in bottom half of a compositor's type case [syn: small letter, lowercase, lower-case letter, minuscule] [ant: capital, capital letter, majuscule, upper-case letter, uppercase]

Definition of 'lowercase'

From: GCIDE
  • lowercase \low"er*case`\, Lower-case \Low"er-case`\, a. (Print.) Pertaining to, or kept in, the lower case; -- used to denote the small letters, in distinction from capitals and small capitals; as, lowercase letters a and b and c etc.. Contrasted with uppercase. See the Note under 1st Case, n., 3. [1913 Webster]