leaning = reclining. Greek. anakeimai, generally translated "sat at meat"; Compare Joh_13:28. Reclining on the divan, his head towards the Lord's bosom, John was in the favoured position, on the Lord's right hand, Judas being on His left.
on = in (Greek. en, as in Joh_13:1).
bosom. Greek. kolpos. Compare the other five occurnces: Joh_1:18. Luk_6:38; Luk_16:22, Luk_16:23. Act_27:39 (creek).