from The American Heritage® Dictionary of the English Language, 4th Edition
- interj. Used as a drinking toast.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- interj. A toast, roughly equivalent to cheers.
from The Century Dictionary and Cyclopedia
- An exclamation of good wishes; hail!
Danish and Norwegian skaal, cup, skoal, from Old Norse skāl, bowl, drinking vessel; see skel-1 in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Nordic skål, which is used for raising a toast and also means bowl. (That there is a relation to English "skull" is urban legend.) (Wiktionary)