For if the woman be not covered, let her also be shorn: but if it be a shame for a woman to be shorn or shaven, let her be covered.
A woman would not like to be "shorn," or, what is worse, "shaven;" but if she chooses to be unveiled in front, let her be so also behind - i:e., "shorn."
A shame - unbecoming (cf. 1 Corinthians 11:13-15). Thus the shaving of nuns is "a shame."