Suffixes change word class, e.g. from verb to noun or noun to adjective, but they can also change meaning
Note: Sometimes there is a spelling change. Here are common examples:
double the consonant,
- sun/sunny,
- fog/foggy
leave out the final ‘e’,
- create/creative,
- fame/famous
leave out the final’s’ before ‘al’,
- politics/political;
- economics/economical
change ‘y’ to ‘i’ before ‘al’,
- industry/industrial
-able /abl/
This suffix (also -ible in some words) is used to form many adjectives from nouns or verbs:
- enjoyable
- comfortable
- knowledgeable (= knows a lot)
- suitable (= right/correct for a particular situation)
Quite often, -able (and -ible) has the meaning ‘can be done’.
- Something that is washable ‘can be washed’.
- drinkable
- comprehensible (= can be comprehended or understood)
- reliable (= can be relied on or trusted, e.g. a car or other machine that never goes wrong or breaks down).
Words ending -able quite often express the opposite meaning by adding the prefix un-:
- undrinkable
- unreliable
- unbreakable (= cannot be broken)
- unsuitable
- uncomfortable
Words ending –ible add the prefix in-:
- incomprehensible
- inflexible (somebody who is inflexible has a fixed idea about something and cannot change quickly or easily; an inflexible timetable cannot be changed easily)
- inedible (= cannot be eaten).
-ful and -less
The suffix -ful often means ‘full of + the meaning of the adjective:
- careful, you are full of care
- if you are helpful you are full of help.
- painful (= hurts a lot)
- useful
- thoughtful (= someone who is thoughtful is kind and always thinks about others; a thoughtful action shows care for others)
The suffix -less means ‘without’ + the meaning of the adjective:
- if you are careless, you do something ‘without care’.
- painless, useless (= has no use or function) thoughtless, jobless and homeless (= with nowhere to live)
Note: You can see that -ful and -less are often used with the same words to form opposites. This is not always true: a person with a home is NOT homeful.
from http://kidspicturedictionary.com/
