tell-tale
n
1 person who reports another's secrets, misdeeds, etc 泄密者; 告发者
Don't be such a tell-tale! 别去告密!
2 mechanical device that serves as an indicator 指示器. adj [attrib 作定语]
revealing or indicating sth 泄露或显示某事的
a tell-tale blush 泄露真情而呈现的面色绯红
the tell-tale smell of cigarette smoke, ie revealing that sb has been smoking 明显的香烟气味（可见有人吸过香烟）.