I had a book of old Icelandic once (I had to give it back, though) that distinguished
between strong and weak adjectives. There were also strong and weak nouns, verbs, etc.
The adjectives didn't quite fit. Are strong and weak (of adjectives) that same as definite
and indefinite (cf http://www.hi.is/~haukurth/norse/grammar/adj.php?colors=1) in the
grammar reference?