Words ending in _y_ preceded by a consonant generally change _y_ into _i_
on taking an additional syllable; as, mercy, _merciful_, _merciless_;
defy, _defied_, _defies_, _defieth_, _defiant_; busy, _busier_,
_busiest_, _business_; ply, _pliers_; porphyry, _porphyritic_.
EXCEPTION I.—_Y_ after a consonant is not changed into _i_
before _ing_ or _ish_; as, _dry_, _drying_, _dryish_.
EXCEPTION II.—Compounds usually retain _y_; as, _mercy-seat_,
_county-town_, _dairy-maid_, _skylight_.
_Remark._—_Dryer_, _dryest_, _dryly_, _dryness_, _shyer_,
_shyest_, _shyly_, _shyness_, are undisputed exceptions to the
rule; and _slyer_, _slyest_, _slyly_, _slyness_, are disputed
exceptions.