I think there exist more than 4 !
(If we include past-tense, plural etc..)

The most appropriate 4 according to me are :

(1) CENTENARY
(2) CONTENDER
(3) COUNTENANCE
(4) CONCATENATION





Other possibilities are :

(1) CATENAE / CATENAS
(2) CONTENDED
(3) CONTENTED
(4) CONCATENATING
(5) CO-ATTENDING