a device for showing the operating condition of some system
a signal for attracting attention
(chemistry) a substance that changes color to indicate the presence of some ion or substance; can be used to indicate the completion of a chemical reaction or (in medicine) to test for a particular reaction
a wrong action attributable to bad judgment or ignorance or inattention; "he made a bad mistake"; "she was quick to point out my errors"; "I could understand his English in spite of his grammatical faults"
an understanding of something that is not correct; "he wasn't going to admit his mistake"; "make no mistake about his intentions"; "there must be some misunderstanding--I don't have a sister"
identify incorrectly; "Don't mistake her for her twin sister"