(bound form) thing; (literary) the outside world as distinct from ones
Phonosemantic compound. 牛 represents the meaning and 勿 represents the sound. Based on the original meaning "variety", depicting the variety of colors on a cow. Later the meaning shifted to "things".
《說文》：“物，萬物也。牛為大物，天地之數，起於牽牛，故从牛，勿聲。”
varicolored cow