Synonyms for join

verb

To put or bring together
unite, connect, link, piece together, blend, combine, merge, consolidate, amalgamate, juxtapose, bring in contact, touch, connect up, couple, conjoin, affix, mix, assemble, stick together, bind together, lump together, fasten, append, attach, secure, tie, annex, agglutinate, bracket, span, intermix, cross with, pair with, leash, yoke, marry, wed, melt into one, copulate, cement, weld, splice, clasp, fuse, lock, grapple, clamp, clip, interlace, entwine, subjoin, involve together, associate; see also unite 1.
Antonyms separate*, sunder, sever.
To enter the company of
enlist, enroll, enter, become a member, associate with, go to, meet, accompany, mingle with, seek, join forces, go to the aid of, follow, rejoin, register, team up with, take up with, tie up with, line up with, be in, sign on, sign up, go in with, fall in with, align, consort, fraternize, throw in with, pair with, affiliate, side with, align with, ally oneself, make one of, take part in, participate, seek a place among, advance toward, go to meet; see also associate 1, unite 1.
Antonyms leave*, desert, quit.
To adjoin
lie next to, be contiguous to, neighbor, border, fringe, butt, trench on, verge upon, be adjacent to, open into, be close to, bound, lie beside, lie near, be at hand, abut, touch, skirt, flank, parallel, rim, hem, abound and abut upon.

join is the general term implying a bringing or coming together of two or more things and may suggest direct contact, affiliation, etc.; combine implies a mingling together of things, often with a loss of distinction of elements that completely merge with one another to combine milk and water; unite implies a joining or combining of things to form a single whole the United States; connect implies attachment by some fastening or relationship roads connected by a bridge, the duties connected with a job; link stresses firmness of a connection linked together in a common cause; associate implies a joining with another or others as a companion, partner, etc. and, in extended use, suggests a connection made in the mind to associate Freud's name with psychoanalysis; consolidate implies a merger of distinct and separate units into a single whole for resulting compactness, strength, efficiency, etc. to consolidate one's debts