Touching one's lips to another person (often lips to lips).
Key passages
So 1:2

May he kiss me passionately with his lips, for your love is better than wine.

Lk 7:38

and standing behind him at his feet weeping, she began to wet his feet with her tears and was wiping them with the hair of her head and was kissing his feet and anointing them with the perfumed oil.

Lk 7:45

You did not give me a kiss, but from the time I entered, she has not stopped kissing my feet.

Lk 22:47–48

While he was still speaking, behold, there came a crowd, and the one named Judas, one of the twelve, leading them. And he approached Jesus to kiss him. But Jesus said to him, “Judas, are you betraying the Son of Man with a kiss?”

Ro 16:16

Greet one another with a holy kiss. All the churches of Christ greet you.