Declarer

• Assertive one
• Someone who admits or acknowledges openly and boldly
• Oath taker, essentially
• Solemn promiser
• One who openly declares
• Oath taker
• Someone who claims to speak the truth

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Avower \A*vow"er\, n. One who avows or asserts.

WordNet Word definitions in WordNet
n. someone who admits or acknowledges openly and boldly someone who claims to speak the truth; "a bold asserter"; "a declarer of his intentions"; "affirmers of traditional doctrine"; "an asseverator of strong convictions"; "an avower of his own great intelligence" ...