A nanoscale photometer

Abbreviation of Aachen. / A surname from German.

(transitive, intransitive) To plunge suddenly into water; to duck; to immerse. / (intransitive) To fall suddenly into water. / (transitive) To put out; to extinguish.

Failure to promote a person to a higher rank. / (US, education) The holding back of a pupil instead of advancing them to the next year of studies.