Stemming normalizes words:
arrival -> arrive
skies   -> sky
riding  -> ride
rides   -> ride
horses  -> hors


Alternatively, instead of word analysis you can use "sounds like" indexing, by using something like soundex or metaphone:


Word      Soundex    Metaphone
stemming  S355       STMNK
peas      P200       PS
peace     P200       PS
please    P420       PLS