conjoin (v.)

late 14c., "to join together, unite; form a union or league," from Old French conjoindre "meet, come together" (12c.), from Latin coniungere "to join together," from assimilated form of com "with, together" (see con-) + iungere "to join together" (from nasalized form of PIE root *yeug- "to join"). Related: Conjoined, conjoining. Conjoined in reference to "Siamese twins" is recorded from 1749.