ENABLE lists 35 words consisting entirely of dots in Morse. "Sissies" and "hissies", which are tied for greatest number of letters, but "hissies" beats out "sissies" for number of dots, at a whopping 18.

There are only 18 words made entirely of dashes, probably mostly because the only vowel available is O. The longest in both letters and dashes is "motmot", which is the bird family containing kingfishers.