1. The arm or leg of the human body.
2. An extreme point of some branch or item.
3. To the absolute height or ultimate degree of something.
ex - TREHM - eh - tee
limit, end, ultimate, apex, outermost
"There were, of course, many survivors of Dain Waris's party; but in the extremity of panic some had swum across the river, others had bolted into the bush." Lord Jim, Joseph Conrad
"'But what,' said she after a short silence, 'are your views? or have you none but that of waiting for Mrs. Ferrars' death, which is a melancholy and shocking extremity?'" Sense and Sensibility, Jane Austen

