The origin of 'trash' is somewhat obscure, but it is most likely borrowed from a Scandinavian source, such as the Old Norse word 'tros' meaning 'fallen leaves and twigs'. This points to an original sense of worthless debris or broken-off pieces. The word entered English in the late Middle English period, initially referring to things of little value or broken items. Over time, its meaning broadened from physical refuse to encompass things of poor quality and, as a verb, the act of discarding or harshly criticizing, metaphorically treating something as worthless.

The word 'trash' is a simplex word of uncertain, but likely Scandinavian, origin. It does not contain separable, meaningful morphemes within its modern English spelling.