Suffixes

A suffix is a word's grammatical ending. If we recognize suffixes, it will help us with grammar and meaning. Many English words have no suffixes. Suffixes are usually unstressed.

1. Types of suffix

There're two types of suffix: (1) derivational and (2) inflectional.

1.1. Derevational suffix

The "derivational" suffix tells us what type of word it is (for example, noun or adjective). For example, -or (in actor) indicates a noun (= someone who does the verb's action).

1.2. Inflectional suffix

The "inflectional" suffix tells us something about the word's grammatical behaviour. For example, -s indicates that a noun is plural. "Derivational" suffixes go before "inflectional" suffixes.
Ex: actor + s.

Inflectional suffixes relate to : -ed form, -er / -est, -ing form, and -s form.

2. Most important derivational suffixes

It's best to look up "derivational" suffixes in a dictionary. Let's see the most important ones below.

2.1. Nouns (people)

-er, -or	actor, driver, manager, writer
-ee	absentee, employee, payee, trainee
-ess	actress, lioness, princess, waitress

2.2. Nouns (abstract)

-ness	darkness, happiness, goodness, greatness
-ity	ability, electricity, quality, sanity
-al	approval, arrival, denial, refusal
-((a)t)ion	intention, invitation, persuasion, reaction
-ment	advertisement, improvement, development, judgement
-hood	boyhood, childhood, sisterhood, widowhood

2.3. Nouns or adjectives

-ist	Buddhist, pianist, realist, typist
-(i)an	human, Indian, Korean, Vitorian
-ese	Chinese, Japanese, Portuguese

2.4. Adjectives

-able	understandable, consumable, enjoyable, readable
-al	central, final, general, national
-ent	different, excellent, present, recent
-ible	accessible, apprehensible, compatible, eligible
-ive	active, attractive, expensive, massive
-ous	anxious, famous, serious, various
-ful	awful, beautiful, useful, wonderful
-less	careless, useless, homeless

2.5. Verbs

-ise*, ize	emphasize, itemize, modernize, realize
-ate	alienate, activate, captivate, deviate, liquidate
-en	deaden, lengthen, soften, widen
-ify	beautify, notify, simplify, terrify

* In general, the spelling of -ise is G.B. (UK). But note that a few verbs are spelled -ise in both G.B. and U.S. For example, advertise, advise, surprise.

2.6. Adverbs

-ly	easily, happily, generally, naturally, quickly
-ward or wards	homeword(s), downward(s), upward(s)

3. Suffixes and stress

The general rule is: suffixes do not have stress, and do not change the stress of the word or stem they are added to:
(1) at'tract → at'tractive
(2) 'happy → 'happiness
(3) 'write → 'writer

But there're many exceptions. Two important exceptions are -'ation, where stress changes to the first syllable of the suffix, and -ity, where the stress changes to the last syllable before the suffix:
(1) in'vite → invi'tation
(2) e'lectric → elec'tricity

Other examples of shifting stress are:
(1) 'photograph → photo'graphic
(2) 'telephone → te'lephonist

I hope this article helps. If you have any question, please leave a comment below.