Skinny, wiry

Hello,
I found this in Harry Potter book 5, chapter 21 page 393 UK edition.
"a stringy Slytherin boy standing just behide Goyle was watching the horse eating with an expression of distaste on his face"

I can't imagine how it looks being a stringy person.

Barney Fife (see above post). From Merriam-Webster online:

Main Entry: stringy
Pronunciation: 'stri[ng]-E
Function: adjective
Inflected Form(s): string·i·er; -est
Date: 1669
1 a : containing, consisting of, or resembling fibrous matter or string Stringy hair. b : lean and sinewy in build : WIRY
2 : capable of being drawn out to form a string : ROPY A stringy precipitate.
- string·i·ness noun

Thank you.