Old English calubald, of West Germanic origin, probably from Latin calvusbald. This was extended to mean unfledged, which led to the present sense immature
this is one of the hidden features of the political machine : the callow age of many its cogs , including some big ones .政治這部機器中許多小齒輪,包括一些大的,他們年輕的年齡是是政治機器隱藏的特點之一。