Style of Songs That Started in the US in the 1940s

This page is the CodyCross answer for the clue below from Pet Shop, Group 356, Puzzle 2 (Dog Muzzles).

Question is: Style of Songs That Started in the US in the 1940s

and the answer is: ROCKMUSIC

Word Meaning:

ROCK MUSIC — (music) A broad genre of popular music, including especially those styles ultimately derived from rock and roll, employing electrical amplification, heavy use of guitars, 4/4 time with strong percussive rhythm on beats two and four (backbeat), and usually themes of bold wildness, rebellion, and sexuality.

Definitions from Wiktionary.