This study explores how care-takers use mimetics -a word class which has a clear sound symbolism- in communicating with their children to investigate the role of iconicity in the input for language development. We approached the question by combining a study of mother-child interaction corpus and a Child-Directed-Speech elicitation experiment, in which care-takers were asked to describe animated actions first to their child and then to an adult experimenter. The results showed that care-takers use mimetics more frequently and use them alone as interjections without embedding them in a sentence for younger children. As their child develop care-takers begin to use mimetics adverbially in a sentence, as they do in Adult-Directed-Speech. This change suggests that care-takers adjust the degree of iconicity in the input according to the child's developmental stage, from bare use to syntactically embedded use of mimetics, and then eventually to non-mimetic conventional words.