The word "laser" is an acronym for "light amplification by stimulated emission of radiation." An object (originally a crystal, it was first discovered with rubies) will "lase" when it is stimulated by broad-spectrum light, the electrons will jump shell and then when they fall back down, emit a particular kind of light. The back-formed verb to lase is frequently used in the field, meaning "to give off coherent light," especially in reference to the gain medium of a laser; when a laser is operating it is said to be "lasing." Roger [explained this](https://mail.google.com/mail/u/0/#inbox/FMfcgzGmtDxDsHdmDtQsPmLClNJwRLjr) better at [[2021-12-25|Christmas 2021 dinner]].