* Short vowels are sounds like the "a" in "cat," the "e" in "bed," the "i" in "pig," the "o" in "hot," and the "u" in "cup."
* Long vowels sound like the letter name, like the "a" in "cake," the "e" in "see," the "i" in "bike," the "o" in "go," and the "u" in "cube."
In the word "boss," the vowel sound is the "o." It sounds like the "o" in "hot," which is a short vowel sound.
Therefore, "boss" is a short vowel word.