Words Easily Confused with One Another

       I've seen and heard this happen with "prostate"  and "prostrate."  One is a male gland; the other is lying flat out on your stomach.  One has one "r"; the other has two "r"s.  They're easy to confuse by sight or sound, not likely meaning.

       Another pair of words is "theses" and "feces."  You hear them, and they sound very much alike, not because the first letters are similar but because the first sounds are.  [th] is made between tip of tongue and upper teeth; [f] is made between upper teeth and lower lip.  The sound in both cases is  frictional air going between related speech organs.

      I always find this one especially perilous:  The Ninety-Five Theses Martin Luther pinned up on the church door in Wittenberg.