lower case

Lower case or lowercase or minuscule letters are the smaller form of letters, as opposed to capital letters: for example, the letter "a" is lower case while the letter "A" is a capital.Originally alphabets were written entirely in capital letters, spaced between well-defined upper and lower bounds. When written quickly with a pen, these tended to turn into rounder and much simpler forms, like uncials. It is from these that the first minuscule hands developed, the half-uncials and cursive minuscule, which no longer stay bound between a pair of lines.
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(a.)
Pertaining to, or kept in, the lower case; -- used to denote the small letters, in distinction from capitals and small capitals. See the Note under 1st Case, n., 3.
  

Noun
1. the characters that were once kept in bottom half of a compositor's type case
(synonym) small letter, lower-case letter, minuscule
(antonym) capital, capital letter, upper case, upper-case letter, majuscule
(hypernym) character, grapheme, graphic symbol