Caller
来自Big Physics
wiktionary
From Middle English callar, equivalent to call + -er.
etymonline
caller (n.)
c. 1500, "one who proclaims," agent noun from call (v.). Meaning "one who announces step changes at a dance" is short for caller-out (1882). Meaning "a social visitor" is attested from 1786; as "one who places a telephone call," 1880.
