Perhaps my favorite linguistic quirks are heteronyms, words that are spells the same but have different pronunciations and different meanings. Words like bow and bow or lead and lead (Okay, that doesn't work too well in print). What can be more confusing for someone trying to learn the language than dealing with words like this?
Lead - As a noun, lead is an elemental metal (symbol Pb). The origin is the German word Lot, meaning plumb weight. As a verb, lead (pronounced LEED) means to be in front and comes from a Saxon word, lithan, meaning to travel.
Bow - The verb, to bend at the waist, is from the Germanic bugon, meaning to bend. That is also the origin for the noun meaning of an archery bow. However, the bow of a ship has its origin in the Dutch word boech, meaning shoulder.
Minute - A personal favorite. Both meanings, one-sixtieth of an hour (stress on the first syllable) and a tiny bit (stress on the second syllable), come from the Latin word minutus, meaning small.