suit·or 
(stər)
(stər)n.
1. One who courts another.
2. A person who makes a petition or request.
3. Law A person who sues in court; a plaintiff; a petitioner.
4. A person or entity trying to acquire a controlling interest in a company, as by purchasing sufficient shares of its stock.
[Middle English, plaintiff, from Anglo-Norman, from Latin secūtor, follower, from secūtus, past participle of sequī, to follow; see sekw-1 in the Appendix of Indo-European roots.]