This lesson aims to show you how Sindarin adjectives are constructed, and much like the Abstract Suffix in the previous lesson, show you how you might use existing rules to create new words.

-eb

This is just listed by Tolkien as 'an adjectival suffix' but it may mean 'full', e.g. Aglar = Glory, Aglareb = Glorious (full glory). It is a much less commonly used suffix than -ui, and I wouldn't advise that you commonly use this for reconstructions.

Attested examples:
Aglareb = Glorious, brilliant
Ereb = Single, alone, lonely
Fíreb = Mortal
Gortheb = Horrible
Maecheneb = Sharp-eyed

-on

This is known as the 'augmentative suffix', and is used to make a noun into a bigger version. (Do not confuse this with the abstract suffix, this is only for making things physically larger). This suffix is quite limited in its usage.

Attested examples:
Ardh = Realm, region, but Ardhon = Great region, great province (the world)
Gaear = Sea, but Gaearon = Ocean

-red

This suffix means 'Ornamentation, highlighting, with the intimation of being fair, used especially on colours and shapes'. This isn't a suffix that exists in English and Tolkien left no attested examples; just a paragraph describing how to use it.

How to add the suffix:
There are no rules of any sort attached to the information (as there are no words listed using this), but we can make some fairly easy inferences, based on how other suffixes attach to words (such as -rim and -ren).

If the word ends in an L, add -LED
If the word ends in an S, remove it and add -THRED
If the word ends in anything else, add -RED
Peng garanred = A bow with red ornamentation/red detail (highlights)
Sigil vorn na malenred = A black necklace (or dagger) with yellow ornamentation/yellow detail (highlights).
Adab na rendred = Building with circular detailing (with the intimation of carving)
Hebaid na glothred = Shoes with white (as snow) ornamentation

-ren

This is a suffix that means 'of' or 'like' and is very commonly used. You can use this for reconstructions very easily. In older Noldorin words this appears as -rin (e.g. Doriathrin, Palathrin). For normal reconstructions, always use -ren!

Attested examples:
Angren = Of iron
Celebren = Silvery (of silver)
Gondren = Stony (of stone, like stone)
Mallen = Golden (of gold, like gold)

This suffix can be used on any noun or verb, and is the equivalent of -LY or -Y on the end of an English word. 

How to add the suffix:
On a noun -
If the word ends in an L, add -LEN
If the word ends in an S, remove it and add -THREN
Otherwise, add -REN

On an I stem verb -
Take the basic stem (e.g. Ped-, Cen-, Car-) and add the suffix as above

On an A stem verb -
Remove the vowel (e.g. Lost instead of Losta-) and add the suffix as above.

Reconstructed examples:
Gais = Steel (Gaithren = Of steel, steely)
Horthren = Speedily (Hortha- = To speed, urge on)
Laegren = Keenly, sharply (Laeg = Keen, sharp)

-ui

This suffix is attested to work with both I stem verbs and nouns. It is the equivalent of the English -able or -ible on the end of a word, or to say 'of xyz' (Breakable, Horrible). It is the most common adjectival suffix in Sindarin.

Attested examples:
Fanui = Cloudy (of clouds)
Gwathui = Shadowy
Melui = Loveable
Lithui = Ashen (of ash)
Rustui = Of copper
úvelui = Unloveable

Reconstructed examples:
Gilui (Elui) = Starry
Rúthui = Angry

-weg

This suffix means 'active in doing', or to add the English -ful or -ive on the end (Awful, Hateful, Delightful, Protective, Narrative etc.)

Attested examples:
Carweg = Active, busy (from the I stem verb Car- = to do)
Madweg = Gluttonous (from the I-stem verb Mad- = to eat)
Pedweg = Talkative, active in saying (from the I stem verb Ped- = to talk)

Reconstructed examples:
Nathaweg = Helpful
Gellweg = Joyful
Hannweg = Thankful