lower case 
noun [mass noun]
Small letters as opposed to capital letters (upper case): the name may be typed in lower case [as modifier]: lower-case letters...
- Of these we have given both the upper case and lower case versions of the 24 classical letters.
- That author gave brown in lower case and Betty in upper case; and, in default of evidence to the contrary, it seems best to go along with the view that Betty is here a proper name.
- Capital letters generally are larger than lower-case letters.
Origin
Referring originally to the lower of two cases of type positioned on an angled stand for use by a compositor (see upper case).