
* = words seen in print

Many words are formed, using suffixes that indicate their meaning. It is, however, not recommendable to invent new words if another term with the same meaning is already well established (e.g. contemporaneousness instead of contemporaneity). And just because adjectives can be formed by adding a -y to a noun, there is no need to invent words like judge-y people (we have "judgmental") or jungle-y green (Roget's Thesaurus already offers more than fifty different adjectives to decribe the color green) just to be genius-y.
Noun Suffixes
-acy (= state or quality: private → privacy)
-al (= act or process of: to refuse → refusal)
-ance, -ence (= state or quality of: to maintain → maintenance; eminent → eminence)
-dom (= place or state of being: free → freedom)
-er, -or (= one who: to protect → protector; to train → trainer)
-ism (= doctrine: social → socialism)
-ist (= one who: pharmacy → pharmacist)
-ity, -ty (= quality of: real → reality)
-ment (= condition of: to argue → argument)
-ness (= state of being: conscious → consciousness)
-ship (= position held: fellow → fellowship)
-sion, -tion (= state of being: translate → translation)
Verb Suffixes
-ate (= to become: grade → graduate)
-en (= to become: height → heighten)
-ify, -fy (= to make or become: terror → terrify)
-ize, -ise (= to become: civil → civilize)
Adjective Suffixes
-able, -ible (= capable of being: eat → edible)
-al (= pertaining to: region → regional)
-esque (= reminiscent of: picture → picturesque)
-ful (= notable for: beauty → beautiful)
-ic, -ical (= pertaining to: myth → mythic)
-ious, -ous (= characterized by: nutrition → nutritious)
-ish (= having the quality of: fiend → fiendish)
-ive (= having the nature of: create → creative)
-less (= without: end → endless)
-y (= characterized by: sleaze → sleazy)
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