Real Dictionary

m.s. in American English
abbreviation: mail steamer
abbreviation: modification of the stem of

manuscript in British English
noun: a book or other document written by hand

Ms
countable noun: An MS or M.S. is the same as an MSc.
title noun: Ms is used, especially in written English, before a woman's name when you are speaking to her or referring to her. If you use Ms, you are not specifying if the woman is married or not.
uncountable noun: MS is a serious disease of the nervous system, which gradually makes a person weaker, and sometimes affects their sight or speech. MS is an abbreviation for 'multiple sclerosis'.

MS in American English
manuscript
abbreviation: millisecond; milliseconds
abbreviation: Mississippi (approved esp. for use with zip code)

ms in British English
abbreviation for: Master of Surgery
noun: a title substituted for Mrs or Miss before a woman's name to avoid making a distinction between married and unmarried women
the internet domain name for: Montserrat

ms.
ms. is a written abbreviation for manuscript.

Ms. in American English
a title free of reference to marital status
abbreviation: manuscript
noun: a title of respect prefixed to a woman's name or position: unlike Miss or Mrs., it does not depend upon or indicate her marital status

MS. in British English
abbreviation for: manuscript