Words that having similar sounds are called homonyms. Within the category of homonyms are two commonly confused concepts: homographs and homophones. Homographs are words that are may have the same spelling, but have different meanings and that may have different pronunciations.
Institution
Institutional
Institutionalize
Institutionalized
Emphasis
Emphasized
Emphasize
Deemphasized
Abbreviation
Abbreviated
Abbreviate
Unabbreviated
Optimum
Optimal
Optimize
Optimally
Suboptimal
Primary
Primarily
Conclusion
Conclusive
Conclude
Conclusively
Drama
Dramatic
Dramatize
Dramatically
Undramatic
Suitability
Suitable
Suit
Suitably
Unsuitable
Agreement
Agreeable
Agree
Agreeably
Unagreeable
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