JOIN, COMBINE, UNITE, CONNECT, LINK, ASSOCIATE, RELATE mean to bring or come together into some manner of union.

JOIN implies a bringing into contact or conjunction of any degree of closeness.

e.g. joined forces in an effort to win

COMBINE implies some merging or mingling with corresponding loss of identity of each unit.

e.g. combined jazz and rock to create a new music

UNITE implies somewhat greater loss of separate identity.

e.g. the colonies united to form a republic

CONNECT suggests a loose or external attachment with little or no loss of identity.

e.g. a mutual defense treaty connected the two nations

LINK may imply strong connection or inseparability of elements still retaining identity.

e.g. a name forever linked with liberty

ASSOCIATE stresses the mere fact of frequent occurrence or existence together in space or in logical relation.

e.g. opera is popularly associated with high society

RELATE suggests the existence of a real or presumed logical connection.

e.g. related what he observed to what he already knew

source: [ゆるゆりの歳納京子と杉浦綾乃が手をつなぐGIF画像｜無料GIF画像検索 GIFMAGAZINE 916103]

link; connect:

〈人が〉 «…に, と» 〈物〉をつなぐ «to» ; 〈2つ以上の物〉をつなぎ合わせる, 結合, 連結, 接合する(together, up)(connect); 〘数〙 【直線で】〈2点〉を結ぶ «by»

e.g. the tap was joined to a pipe

e.g. join the paragraphs together.

become linked or connected to:

〈川･道路などが〉…と合流する(meet)

e.g. where the River Drave joins the Danube.

connect (points) with a line:

e.g. join up the points in a different color.

no object, with adverbial unite to form one entity or group:

〈複数の物が〉つながる, 結びつく; 〈川･道路などが〉合流する, 接する; 隣接する

e.g. they joined up with local environmentalists

e.g. countries join together to abolish restrictions on trade.

become a member or employee of:

〈人が〉〈組織･会社など〉の一員になる, 仲間になる; 〈大学〉に入学する(｟かたく｠ enroll at/in); 〈軍隊〉に入隊する(｟かたく｠ enlist in)

e.g. she joined the department last year.

take part in:

〖join A(for B)/(in doing)〗 〈人が〉(Bのために, …するために)A〈人〉に加わる, 参加する; 〈人〉と合流する, 落ち合う; 〈活動など〉に参加する

e.g. I joined the demonstration

〖join in A〗 〈人が〉(楽しむために) 【人と】A〈活動〉に参加する, 加わる «with» (!受け身にしない)

e.g. no object : I joined in and sang along.

no object (join up) become a member of the armed forces:

join up:｟英｠ 入隊する(｟かたく｠ enlist)

e.g. her brothers joined up in 1914.

come into the company of:

e.g. after the show we were joined by Jessica's sister.

support (someone) in an activity:

〈人が〉 «人と/…するのに» 協力, 協同する, 同調する(in, up, together) «with/in doing, to do»

e.g. I am sure you will join me in wishing him every success.

a place or line where two or more things are connected or fastened together.

接合箇所, 点, 線; 合流点; 縫い目, 継ぎ目

formal begin fighting.

see club1.

combine efforts.

hold each other's hands.

work together:

e.g. education has been shy to join hands with business.

joinable adjective

Middle English: from Old French joindre, from Latin jungere ‘to join’.