Just like people, words are born, live, and die. (They just live a lot longer.) Over the centuries, in other words, our ancestors developed new words, changed them in different ways to express different things, and then, for one reason or another, stopped using some words. Our interest here is in how words have changed. Understanding that can help you improve your vocabulary -- and your writing.
Some words are very simple -- man, friend, draw. Other words, however, are formed from these simple words: man -- manly, manfully; friend -- friendly, friendship, unfriendly; draw -- drawing, withdraw. The parts that form such words are called roots, prefixes, and suffixes.
The Root of a word is usually a simple English word without a prefix or a suffix, such as move, see, hold, press. Prefixes and suffixes can be added to these words to make new words -- pressure, impression, suppress. Some roots are not English words. For example, from the Latin, we have the roots vert and duce from which English gets words like convert and introduce.
A Prefix is a significant syllable or word placed before the root. In mistake, undertake; mis and under are prefixes.
A Suffix is a significant letter or syllable placed after the root. In amused, amusement, amusing; d, ment, and ing are suffixes.
All words formed from the same root are said to belong to the same family of words; thus, betake, mistake, retake, partake. overtake, undertake, etc., belong to a family of words. The following words belong to another family: Divert, convert, avert, pervert, controvert, invert, subvert, revert, perversion, diversity, introverted, uncontroverted, etc.
Like all families, word-families
can be viewed as "small" or "big." With people, a "small" family
consists of parents and their children. A "big" family extends to aunts,
uncles, grandparents, cousins, and beyond to include everyone related by
blood. A "small" word family consists of one basic word and variations
that change how it can be used (noun, adjective, verb, adverb). Within
these variations of part of speech, other variations can change the meaning
from naming an act ("describing") to the result of the act ("description")
or to the doer of the act ("describer") or to the quality of the act ("descriptiveness").
"Big" word families are usually created by prefixes that fundamentally change the meaning. For example, the "big" family of the root motion includes words such as emotion, promotion, commotion, and demotion.