"meaningless repetition of words and phrases," 1876, from German (von Romberg, 1865), from Greek ēkhō (see echo (n.)) + lalia "talk, prattle, a speaking," from lalein "to speak, prattle," of echoic origin.
Entries linking to echolalia
echo n.
mid-14c., "sound repeated by reflection," from Latin echo, from Greek ēkhō, personified in classical mythology as a mountain nymph who pined away for love of Narcissus until nothing was left of her but her voice, from or related to ēkhē "sound," ēkhein "to resound," from PIE *wagh-io-, extended form of root *(s)wagh- "to resound" (source also of Sanskrit vagnuh "sound," Latin vagire "to cry," Old English swogan "to resound"). Related: Echoes. Echo chamber is attested from 1937.