To join in the attack

Greek: συνεπιτιθημι [sunepitithêmi] (Verb). To help in putting on, put on still more. Middle: to attack together, join in attacking. See: συντιθημι [suntithêmi].

συνεπιτιθημι [sunepitithêmi] appears 1 time in the NT:

(1) Acts 24: 9
The Jews also joined in the attack, asserting that these things were so. (New American Standard Bible). - συνεπεθεντο [sunepethento] Aorist Indicative Middle, 3 pl.

- And the Jews also assented, saying that these things were so. - (KJV) Variant: συνεθεντο [sunethento] (συντιθημι [suntithêmi] ).