What's the difference between checkmate and checkmated?

Checkmate

Definition:

(n.) The position in the game of chess when a king is in check and cannot be released, -- which ends the game.
(n.) A complete check; utter defeat or overthrow.
(v. t.) To check (an adversary's king) in such a manner that escape in impossible; to defeat (an adversary) by putting his king in check from which there is no escape.
(v. t.) To defeat completely; to terminate; to thwart.

Example Sentences:

(1) And those are unresolvable, and you're checkmated whichever way you go."
(2) He gave me a sleepy-lidded smile, the sort I imagine a grandmaster might give on checkmating someone easily.
(3) Non-violence was a creative doctrine in the South because it checkmated the rabid segregationalists who were thirsting for an opportunity to physically crush Negroes.
(4) We are not checkmated.” Sanders’s campaign is more often compared to Obama’s in 2008 – when the Illinois senator surprised Clinton and the political establishment by pulling off an unexpected victory – than to Jackson’s.

Definition:

Example Sentences:

(1) And those are unresolvable, and you're checkmated whichever way you go."
(2) He gave me a sleepy-lidded smile, the sort I imagine a grandmaster might give on checkmating someone easily.
(3) Non-violence was a creative doctrine in the South because it checkmated the rabid segregationalists who were thirsting for an opportunity to physically crush Negroes.
(4) We are not checkmated.” Sanders’s campaign is more often compared to Obama’s in 2008 – when the Illinois senator surprised Clinton and the political establishment by pulling off an unexpected victory – than to Jackson’s.