English Language Arts
Grade 9
15 min
Words with -able and -ible
Words with -able and -ible
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Introduction & Learning Objectives
Learning Objectives
Differentiate between the suffixes -able and -ible based on etymological roots and spelling conventions.
Correctly spell and use a variety of academic and literary words ending in -able and -ible.
Analyze how the suffixes -able and -ible alter the meaning and function of a root word, changing it into an adjective.
Apply knowledge of these suffixes to infer the meaning of unfamiliar words encountered in complex texts.
Construct sophisticated sentences that accurately use words with -able and -ible to enhance descriptive and argumentative writing.
Evaluate an author's word choice, specifically their use of -able/-ible adjectives, to understand tone and characterization.
Ever wondered why a character is 'likable' but a decision is 'defens...
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Key Concepts & Vocabulary
TermDefinitionExample
SuffixA morpheme (a meaningful unit of language) added to the end of a word to change its meaning or function.In the word 'readable', the suffix '-able' changes the verb 'read' into an adjective meaning 'capable of being read'.
Root WordThe core of a word that carries the primary meaning. Suffixes and prefixes are attached to it.'Accept' is the root word of 'acceptable'.
Complete Root WordA root word that can stand alone as a complete, functional word in English.The word 'depend' is a complete root word, which is why we form the word 'dependable'.
Latin RootA word part derived from the Latin language that is not a standalone word in English but forms the basis for many English words.'...
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Key Rules & Conventions
The Complete Root Word Rule for -able
If the root is a complete English word, the suffix is almost always -able.
This is your primary guide. If you can remove the suffix and are left with a word you recognize (e.g., read, wash, accept), use -able. This rule applies even if you have to drop a final 'e' from the root (e.g., advise -> advisable).
The Latin Root Rule for -ible
If the root is not a complete English word (often a Latin root), the suffix is usually -ible.
When you remove the suffix and are left with a part that isn't a standalone word (e.g., cred-, aud-, terr-), the correct suffix is typically -ible. Examples: credible, audible, horrible.
The Soft 'c' and 'g' Convention
Words ending in -ceable and -geable keep the 'e...
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Challenging
Given the Latin root *credere* (to believe), and the knowledge that adjectives are often formed from a related Latin stem, which of the following is the correct adjective form and justification?
A.Credable, because the related English word 'credit' is a complete word.
B.Credible, because the adjectival form is based on the Latin root, which is not a standalone English word.
C.Credible, because it is a known exception that must be memorized.
D.Credible, because it sounds more professional than 'credable'.
Challenging
Evaluate the following sentence from a draft of a fantasy novel: 'The ancient, unchangeible laws of the kingdom could not be broken.' Which statement provides the most accurate critique of the underlined word?
A.The word is spelled correctly and used effectively to create an archaic tone.
B.The word is misspelled; it should be 'unchangible' because the root 'change' has a Latin origin.
C.The word is misspelled; according to the 'Soft g Convention', the 'e' must be kept, resulting in 'unchangeable'.
D.The word is used incorrectly; 'immutable' would be a more appropriate choice for ancient laws.
Challenging
The word 'resistible' correctly follows the 'Complete Root Word Rule' ('resist' + '-ible' is an exception pattern, but let's assume it follows the base rule for the antonym). Why then is its antonym, 'irresistible', listed in the tutorial as a key exception to memorize?
A.Because the prefix 'ir-' changes the suffix from -able to -ible.
B.It is an error in the tutorial; 'irresistable' should be the correct spelling.
C.Because while 'resist' is a complete word, the historical Latin form (*resistere*) has so strongly influenced the negative form that it adopted the -ible suffix, creating an exception to the English rule.
D.Because all words that start with the prefix 'ir-' must use the suffix -ible.
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