Dixon claims, in volume 2 of Basic Linguistic Theory, that there is no
language which doesn't have a class of adjectives which differs in at least
some way from nouns and/or verbs. I have until now thought that Sohlob was
a counterexample (a rather weak one being a conlang!) but I just realized
that adjectives and nouns in Sohlob differ from each other in at least two
obvious ways:

1. While adjectives can be used as nouns of quality — for example _raz_
means both 'green' and 'greenness' — nouns cannot function as adjectives
without derivation — for example _zoǧd_ means 'elephant' but not
'elephant-like', which is _zoǧdom_. Also 'elephanthood' is _zoǧdaf_ and
'elephant-likeness' is _zoǧdomaf_, while _?razaf_ as a noun is of
questionable grammaticality — if possible it means 'the quality of having
green color to the exclusion of other colors'.

2. Only adjectives can take suffixes of comparison and degree. Things are a
little muddied by the fact that the suffix meaning 'exceedingly X' is also
_-Af_, so that the natural interpretation of _razaf_ is 'exceedingly
green', but I'm quite certain that _zoǧdaf_ *cannot* mean 'exceedingly
elephant' whatever that would mean; you would have to say _krobaf mum zoǧd_
literally 'exceedingly much like elephants', since _zoǧtah_ 'an elephant'
would mean 'a certain elephant' here. I'm pretty certain that _-Af_ the
degree suffix and _-Af_ the derivational suffix are quite distinct. It is
very possible that they weren't homophones at an earlier stage of the

However I haven't figured out to what degree these differences proceed from
semantics rather than grammar.