Verb niptō (to wash) in the Gospels-Acts

(Translation from NRSV)

Matthew

6: 17But when you fast, put oil on your head and wash (niptō) your face,
15: 2"Why do your disciples break the tradition of the elders? For they do not wash (niptō) their hands before they eat."

Mark

7: 3(For the Pharisees, and all the Jews, do not eat unless they thoroughly wash (niptō) their hands, thus observing the tradition of the elders;

John

9: 7saying to him, "Go, wash (niptō) in the pool of Siloam" (which means Sent). Then he went and washed (niptō) and came back able to see.
9: 11He answered, "The man called Jesus made mud, spread it on my eyes, and said to me, 'Go to Siloam and wash (niptō).' Then I went and washed (niptō) and received my sight."
9: 15Then the Pharisees also began to ask him how he had received his sight. He said to them, "He put mud on my eyes. Then I washed (niptō), and now I see."
13: 5Then he poured water into a basin and began to wash (niptō) the disciples' feet and to wipe them with the towel that was tied around him.
13: 6He came to Simon Peter, who said to him, "Lord, are you going to wash (niptō) my feet?"
13: 8Peter said to him, "You will never wash (niptō) my feet." Jesus answered, "Unless I wash (niptō) you, you have no share with me."
13: 10Jesus said to him, "One who has bathed does not need to wash (niptō), except for the feet, but is entirely clean. And you are clean, though not all of you."
13: 12After he had washed (niptō) their feet, had put on his robe, and had returned to the table, he said to them, "Do you know what I have done to you?
13: 14So if I, your Lord and Teacher, have washed (niptō) your feet, you also ought to wash (niptō) one another's feet.