Learn how to say Lackluster correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word lacklustre:
1lacking in vitality, force, or conviction; uninspired or uninspiring:
no excuses were made for the team’s lacklustre performance
2(of the hair or the eyes) not shining; dull:
the conditioner will revitalize lacklustre hair
The ending of lacklustre is -tre (the spelling lackluster is American).