(quantum mechanics, quantum electrodynamics) A small difference between the energy levels 2S_½ and 2P_½ of the hydrogen atom, not predicted by the Dirac equation, whose detection in the Lamb–Retherford experiment of 1947 foreshadowed the development of quantum electrodynamics (in which the discrepancy is explained to be an effect of the emission and re-absorption of virtual photons); such a difference between otherwise expectedly equal energy levels of hydrogen or any other type of atom.

plural of ewe lamb

A female lamb. / A poor person's sole possession (in reference to the Bible, 2 Samuel xii).

(childish) A lamb or sheep. / Someone who is submissive, especially a husband or boyfriend.

plural of baa-lamb

(countable) A lamb raised for slaughter wholly inside a building. / (uncountable) The meat of such a lamb.

plural of house lamb

(obsolete, humorous) A barrister / (obsolete, humorous) A customer at a bar (place that sells alcoholic drinks)

(obsolete, card games) The game of lansquenet.

(slang, archaic, gambling) Of a bookmaker: to win all of his bets, in the case where nobody backed the winner.