numbing — deprived of physical sensation or the ability to move: fingers numb with cold.
plumbing — a small mass of lead or other heavy material, as that suspended by a line and used to measure the depth of water or to ascertain a vertical line. Compare plumb line.
thumbing — the short, thick, inner digit of the human hand, next to the forefinger.
Three-syllable rhymes
becoming — A piece of clothing, a colour, or a hairstyle that is becoming makes the person who is wearing it look attractive.
forthcoming — coming, forth, or about to come forth; about to appear; approaching in time: the forthcoming concert.
Four-or-more syllable rhymes
second coming — the coming of Christ on Judgment Day.
unbecoming — detracting from one's appearance, character, or reputation; unattractive or unseemly: an unbecoming hat; unbecoming language.