1.Definition:
Macmillan English-Chinese Dictionary: a new part added to the beginning or end of a word that changes its meaning.

Concise Oxford English Dictionary: Grammar an addition to the base form or stem of a word that modifies it’s meaning or creates a new word.

Collins CoBuild Dictionary:"An affix is a letter or group of letters, for example `un-' or `-y', which is added to either the beginning or the end of a word to form a different word with a different meaning. For example, `un-' is added to `kind' to form `unkind'. Compare prefix and suffix."
In a word, affix is a linguistic element added to the beginning or end of a word or root to produce a derived or inflected form which has different meaning from the original : -ful in cheerful, grateful, faithful is a derivational affix ; -s in hands, weeks, years is an inflectional affix .


2.The types of affixes:
There are 3 types : prefix, suffix, infix

1. prefix: a group of letters that is added to the beginning of a word to adjust or qualify its meaning. For example, the prefix ‘un-’ is added to the word ‘happy’ to form ‘unhappy’.


List of prefix:

un-: unture
dis-: dislike
in-: informal
im-: immoral
ir-: irregular
il-: illegal
non-: non-existent
re-: retell
mis-: misspell
co-: coeditor
pre-: preview
counter-: countertreat
anti-: anti-tank
over-: overdo
under-: underfeet
post-: post-election
fore-: foretell
self-: self-respect
super-: superman
sub-: subway
inter-: international
tele-: telescope
trans-: transport
micro-: microfilm
mini-: minibus
semi-: semi circle
vice-: vice-premier
mono-: monoplane
bi-: bicycle
tri-: triangle
poly-: polygamy
multi-: multiracial
auto-: automatic

2. Suffix:a group of letters that is added to the end of a word to form a new word. For example, ‘-ant’ is added to the word ‘ignore’ to form ‘ignorant’.


List of suffix:

-ful: cheerful
-less: careless
-ish: selfish
-ive: active
-ous: famous
-able: comfortable
-ible: sensible
-ic: poetic
-ant: ignorant
-ly:weekly
-al: critical
-y: rainy
-ent: different
-ary: imaginary
-some: troublesome
-like: childlike
-en:golden
-ate: fortunate
-ly: helpfully
-ward: northward
-wise: likewise
- ize: realize
-en : widen
-ify: beautify
-ate :originate

3. Infix :a group of letters that is added within a word; these are rare in English, though ‘cupful’ can be made plural as ‘cupsful’ by inserting the plural ‘s’ as an infix. Infixes often appear as linking vowels between prefixes and stems. For example, the final letters of ‘narco-’ and ‘calci-’. They are also found between a stem ending in a consonant and a suffix beginning with one, as with ‘-ferous’, which frequently appears as ‘-iferous’, The only examples of such linking vowel infixes here are ‘-i-’ and ‘-o-’.



3.Cited:

1.http://www.affixes.org/typesofaffix.html

2.http://grammar.about.com/od/ab/g/affixterm.htm

4. More read:

http://en.wikipedia.org/wiki/Affix