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 .政治这部机器中许多小齿轮,包括一些大的,他们年轻的年龄是是政治机器隐藏的特点之一。