Is there an affixing rule to drop the final 't' when adding the affix 'cy'. I assumed there exists two different suffixes, 'ent' and 'ency' (or 'ant' and 'ancy'). Hundreds of examples of those:
constitu+ent/ency consult+ant/ancy conting+ent/ency
but there's another, smaller set of words that don't end in an 'ent' or 'ant', they seem to simply drop the 't' before 'cy'.
diplomat+cy => diplomacy
idiot+cy => idiocy
infant+cy => infancy
it seems more consistant to use the 'drop the t' rule in both cases (consistant+cy => consistancy) and treat this as the standard suffixing rule. In that case, the first three examples (only marking the affixes under consideration) become:
constitu+ent+cy => constituency consult+ant+cy => consultancy conting+ent+cy => contingency
there is one troubling exception:
bankrupt+cy => bankruptcy
There are also words that looks like 'drop the t' but are clearly two different suffixes: +ate and +acy.
intimate +cy => intimacy
private+cy => privacy
But I can't see how to generalize different suffixes to 'idiot' and 'idiocy' and similar.