From Longman Dictionary of Contemporary Englisheven-temperedˌeven-ˈtempered adjective CALMsomeone who is even-tempered is calm and does not easily become angry SYN placid
Examples from the Corpus
even-tempered• They will stay even-tempered from morning to night.• Charles had been Lord of the Scaffold since 1699, contemporaries describing him as a gentle and even-tempered man. 