holler (v.) Look up holler at Dictionary.com
1690s, American English, variant of hollo (1540s) "to shout," especially "to call to the hounds in hunting," which is related to hello. Compare colloquial yeller for yellow, etc. Related: Hollered; hollering.
holler (n.) Look up holler at Dictionary.com
1896, from holler (v.); earlier hollar (1825). As a style of singing (originally Southern U.S.), first recorded 1936.