> <DT>&AElig;>
> <dd>Æ - capital AE diphthong (ligature)
In modern typographic practice it's probably best to call that a ligature.
Depending on the state of the language it's being used with, it may also be a
digraph (i.e., a compound character made up of two components). It shouldn't
be called a dipthong, because that has to do with pronunciation, not
orthography/typography. (A dipthong is a compound vowel consisting of at
least two vocalic components, such as the sounds of all the long vowels in
most dialects of modern English [long "a" = "eh" + an off-glide].)
Jim Mason