In English, an adjective can be declined (modified) to become a comparative: that is, “green” can become “greener“. This is not generally done in Talossan; instead, you simply must use the word pü (= more) in front of the adjective.
This should not seem all that strange, though; notice that in English, there is rarely a declension for an adjective to indicate its lessening — so although “greener” means “more green”, if you need to say “less green”, then, well, you need to say “less green” — there is no single word for that.
And in Talossan, this is also what you must do, using the word míus (= less). So one way to say “he is not as tall as I” would be o isch míus inalt qe éu.
Be careful to use the subject pronoun properly; a lot of people are careless with the distinction between subject pronouns and object pronouns in English, incorrectly using the object pronoun in comparative sentences such as “he is taller than me”. This sentence should properly be “he is taller than I”, and you should be sure (in both Talossan and English, frankly) to use the subject pronoun in cases like these: o isch pü inalt qe éu (= he is more tall than I).
Notice that both pü and míus are words that are usually written with their consonant mutation indicated, becoming phü and mhíus after prepositions that end in vowels, or after la (= the).
There are two adjectives in Talossan, however, that do have a single-word way to indicate more and less of them. These two adjectives are ben (and its feminine form buna), which means “good”, and mal, which means “bad”. In other words, while there is no single Talossan word for “greener”, there is a single word for both “better” and “worse”. These words are miglhor (= better) and pior (= worse). Just as with pü and míus, both miglhor and pior are words that are often seen in their mutated forms after vowels: mhiglhor and phior.
To indicate “better”, both pü ben (literally = more good) and miglhor are proper. This is different than in English, where you must say “better” and to say “more good” is improper. Note, though, that pü mighlor and míus pior are improper in Talossan in the same way that “more better” and “less worse” are improper in English.
Although there are single-word Talossan equivalents for “better” and “worse”, there are not Talossan equivalents for “best” and “worst”. Instead, the superlative (such as “best”, “worst”, and “greenest”) is expressed simply by creating a comparative, and putting a definite article in front of it. So while pü virt would mean “greener”, el pü virt (or, if referring to a feminine gender noun, la phü virt) means greenest. Yes, it looks like it would be translated to English as “the more green”, but the fact is that while pü means “more”, el pü means “most”.
The special comparative words miglhor and pior are also made into “best” and “worst” in the same way, by simply preceding them with a definite article (el miglhor, la mhiglhor, el pior and la phior).
This use of the definite article can sometimes lead to ambiguity: does el viind pü deliçal mean “the more delicious meat” or “the most delicious meat”? Usually, context is clear as to whether the noun and adjective both “use” the article, but do not be afraid to repeat the article to emphasise the superlative: el viind el pü deliçal (= the most delicious meat).
Be sure to use the proper definite article for the gender of the noun in question. That is: el porc el pü negreu (= the blackest pig), and la valeina la phü neagra (= the blackest whale).