How to say "affiliation" in Japanese

• 所属しょぞくJLPT N1approx.Common
  suru verb, intransitive verb, no-adjectiveCovers affiliation as the state of belonging to or being attached to a group, organization, or institution; use it when saying which organization a person or company belongs to, not for the act of joining.
  私はどのクラブにも所属しょぞくしていない。↗

  I don't belong to any club.
• 加盟かめいCommon
  noun, suru verb, intransitive verbAffiliation as the act of an organization joining an association, league, or agreement — a club joining a league, a country acceding to a treaty; the affiliated party is itself a body.
  加盟国かめいこく中ちゅう数カ国すうかこくは、Ｇ７の協定きょうていに従したがうことにあいまいな態度たいどを見みせています。↗

  Some member countries have been lax in abiding by G-7 agreements.
• アフィリエイトCommon
  nounThe loanword, used for the commercial affiliate arrangement — a website or publisher earning commission by referring customers to a business; it does not mean belonging to an organization.
• 加入かにゅうJLPT N1approx.Common
  noun, suru verb, intransitive verbCovers affiliation as the act of joining a club, organization, or similar body and becoming a member; it points to the act itself, while 所属 names the state of belonging that results.
  まさかの時ときのために彼かれは保険ほけんに加入かにゅうした。↗

  He insured himself for a rainy day.
• 合併がっぺいJLPT N1approx.Common
  noun, suru verb, transitive verb, intransitive verbNot a way to say 'affiliation' in the belonging sense: it means a merger or amalgamation — companies or towns combining into one — and is seldom the word you want for affiliation.
  ２社しゃは合併がっぺいを計画けいかくしている。↗

  The two companies plan to unite.

Use 所属 for the state of belonging to an organization, 加盟 for a group joining an association or agreement, 加入 for the act of becoming a member, 「アフィリエイト」 for the web-marketing affiliate sense, and 合併 only for mergers.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 所属しょぞくbelonging to (a group, organization, etc.)
• 加盟かめいjoining (an association, agreement, etc.)
• アフィリエイトaffiliate
• 加入かにゅうjoining (a club, organization, etc.)
• 合併がっぺいmerger (of companies, towns, etc.)
• 係属けいぞくconnection
• 旗色はたいろone's allegiance