Muscle

[nightowl]

What one same seven-letter word can mean a certain muscle of the human body and also mean a triangle with all three sides of different lengths

[Quizmonster]

'Scalene' describes a triangle with such sides and also a neck muscle.

[sft42]

Scalene is quite correct but I have also seen "Deltoid" used as this answer in crosswords ocassionally as it means triangular as well.

[Quizmonster]

I obviously agree, S, that 'deltoid ' is the name of a muscle and it is also used to signify 'triangular'. However, I don't believe I have ever heard it used to mean - specifically, as in the question - "a triangle with all three sides of different lengths". (Mind you, that's not to say it never has been so used!) Cheers