How many relatively common singular nouns can you think of that, when you remove an "s", become a relatively common plural noun?

For example: PRINCESS (singular) becomes PRINCES (plural).

I know of at least four more, one of which only has one "s" to begin with.

(In reply to I believe there are more than these.... (spoiler) by Dej Mar)

Firstly I detect an error in #3.

Secondly #28 -31?  When I initially read the problem I was in two minds as to what was meant but I dismissed the concept offered here having decided that S4TD meant something like
 XXXXS →XXXX, ie the first word ends in one 's' and in singular but by the removal of that 's' we get a plural noun.

"to begin with"? 
Three of those four words (28-31) have an interesting quality in that they might be singular or be collective.

Posted by brianjn on 2009-03-24 20:51:57