name-calling (n.)

"the use of opprobrious epithets," 1846, fromcall(someone or something)names "attempt to put someone or something in a bad light by affixing to him or it a word of unpleasant connotation" (1590s); see call (v.) + name (n.). 

WHEN dunces call us fools without proving us to be so, our best retort is to prove them to be fools without condescending to call them so. [The Rev. C.C. Colton, "Lacon: or Many Things in Few Words," London, 1823]