英語の語形成：48パターン完全ガイド
英語の単語がどのように作られるかを理解することは、まさに超能力です。一度も見たことのない何千もの単語の意味を推測できるようになります。このガイドでは6つの主要な語形成プロセス（接頭辞、名詞接尾辞、形容詞接尾辞、動詞接尾辞、複合語、品詞転換）を、各パターンの実例とともに解説します。以下で検索するかカテゴリでフィルタして探してみてください。
48 items · 6 topics
"un-"
not; reverse the action (unhappy, undo, unclear)
"She felt unhappy after hearing the unexpected news."
"dis-"
not; opposite of (disagree, disappear, dishonest)
"I completely disagree with the decision they made."
"re-"
again; back (rebuild, return, reconsider)
"We need to reconsider our strategy after these results."
"pre-"
before (prepare, predict, preview)
"Please preview the document before sending it."
"over-"
too much; above (overwork, overcome, overestimate)
"She tends to overestimate how long tasks will take."
"mis-"
wrongly; incorrectly (misunderstand, mislead, misuse)
"He misunderstood the instructions and went the wrong way."
"inter-"
between; among (international, interact, interconnect)
"The two teams interact closely on every project."
"sub-"
under; below (subway, subtitle, submarine)
"Add subtitles so viewers can follow along easily."
"-tion / -sion"
forms nouns from verbs (education, permission, decision)
"Her decision to study abroad changed everything."
"-ment"
forms nouns showing a state or result (development, movement)
"The development of the project took two full years."
"-ness"
forms nouns from adjectives (happiness, darkness, kindness)
"The kindness of strangers surprised her deeply."
"-er / -or"
forms agent nouns — person doing sth (teacher, actor)
"The actor delivered a truly unforgettable performance."
"-ity"
forms abstract nouns from adjectives (creativity, ability)
"Her creativity made the campaign stand out completely."
"-ism"
forms nouns for doctrines or practices (journalism, realism)
"He studied journalism at the city university."
"-ist"
forms nouns for a person following a belief (artist, pianist)
"The pianist performed three Chopin nocturnes flawlessly."
"-ance / -ence"
forms nouns of state or quality (performance, confidence)
"Confidence is the key to a great job interview."
"-able / -ible"
capable of; worthy of (readable, flexible, reliable)
"This contract is not readable without legal training."
"-ful"
full of; having (helpful, powerful, colourful)
"Her helpful feedback improved the final draft significantly."
"-less"
without; lacking (careless, hopeless, wireless)
"He was careless with the details and the client noticed."
"-ous / -ious"
having the quality of (famous, mysterious, generous)
"The generous donation covered all the event costs."
"-al / -ical"
relating to (musical, logical, cultural, practical)
"Her practical approach saved the team a lot of time."
"-ive"
tending to; having a nature of (creative, active, sensitive)
"The creative director redesigned the whole brand identity."
"-ish"
somewhat; like (childish, greenish, selfish, stylish)
"She gave a stylish presentation that impressed everyone."
"-y"
having the quality of (cloudy, windy, tricky, noisy)
"The noisy café made it hard to concentrate on work."
"-ise / -ize"
to make; to cause to become (organise, modernise)
"We need to modernise the system before the launch."
"-en"
to make more; to become (strengthen, brighten, widen)
"Regular practice will strengthen your speaking skills."
"-ify / -fy"
to make; to cause to be (simplify, clarify, classify)
"Could you clarify what you meant in the second paragraph?"
"-ate"
to act or cause (communicate, generate, motivate)
"Great leaders know how to motivate their entire team."
"-en (causative)"
to make something happen (darken, weaken, loosen)
"The bad news seemed to darken the mood in the room."
"-ify (intensify)"
to make more intense (intensify, diversify, amplify)
"Adding music helped amplify the emotional impact."
"-ise (socialise)"
to engage in an activity (socialise, advertise, supervise)
"She loves to socialise after work with her colleagues."
"-ate (originate)"
to produce or begin (originate, innovate, evaluate)
"The idea originated from a simple customer complaint."
"sunflower"
closed compound noun: sun + flower
"The sunflower turned its head slowly toward the afternoon light."
"well-known"
hyphenated compound adjective: well + known
"She is a well-known author in the field of linguistics."
"swimming pool"
open compound noun: two separate words
"The hotel swimming pool was open until midnight."
"break-through"
hyphenated compound: a major discovery or achievement
"The research team announced a breakthrough in battery technology."
"heartbeat"
closed compound: the rhythm of the heart
"His heartbeat quickened as he opened the envelope."
"high-tech"
hyphenated compound adjective: advanced technology
"The factory uses high-tech robotics on the assembly line."
"workforce"
closed compound: the total body of workers
"The company is planning to expand its workforce this year."
"self-esteem"
hyphenated compound: confidence in oneself
"Praise from a mentor can greatly boost a student's self-esteem."
"to google (verb)"
conversion: noun Google → verb meaning to search online
"Just google it — you'll find the answer in seconds."
"a must (noun)"
conversion: modal must → noun meaning something essential
"A good dictionary is a must for any serious language learner."
"blended: brunch"
blend of breakfast + lunch
"We went for a long, lazy brunch on Sunday morning."
"blended: smog"
blend of smoke + fog
"The city was covered in a thick smog all week."
"clipping: exam"
clipped from examination
"The exam results will be published on Friday morning."
"clipping: ad"
clipped from advertisement
"The ad campaign went viral within the first 24 hours."
"acronym: NASA"
National Aeronautics and Space Administration
"NASA announced a new mission to the outer planets."
"acronym: laser"
Light Amplification by Stimulated Emission of Radiation
"The surgeon used a laser to correct her vision precisely."
よくある質問
英語の語形成とは何ですか？
語形成とは、英語で新しい単語が作られるプロセスのことです。主なプロセスには、接辞付加（接頭辞・接尾辞の追加）、複合（2つの単語の結合）、品詞転換（接辞を追加せずに品詞を変える）、および混成語、省略語、頭字語などの特殊なプロセスがあります。
語形成を学ぶことが重要なのはなぜですか？
語形成のルールを知ることで、未知の語彙を解読し、能動的な語彙をはるかに速く増やし、より自然に聞こえるようになります。たとえば、-tionが名詞を作ることを知っていれば、"organisation"、"communication"、"motivation"がすべて動詞から派生した名詞だとわかります。
接頭辞と接尾辞の違いは何ですか？
接頭辞は単語の先頭に付けられます（"unhappy"のun-）。接尾辞は末尾に付けられます（"happiness"の-ness）。接頭辞は通常、品詞を変えずに意味を変えます。一方、接尾辞は品詞を変えることが多く、たとえば動詞を名詞に変えます。
まず学ぶべき最も役立つ接頭辞はどれですか？
最も一般的なun-、re-、dis-、pre-から始めましょう。これら4つだけで英語の何千もの日常語に登場します。慣れたら、学術英語やビジネス英語で非常によく使われるover-、mis-、inter-、sub-に進みましょう。
IELTSやCambridgeなどの試験で語形成は出題されますか？
はい。語形成はCambridgeの試験（B2 First、C1 Advanced）で独立した問題タイプとして出題され、与えられた単語の正しい形を空欄に記入する問題が出ます。IELTSのリーディングやライティングにも間接的に関わります。語族と一般的な接辞を理解することで、スコアが大幅に向上します。
語形成のパターンを実際の英語で聞くことが、最も速く定着させる方法です。
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