(physics) A minor stable isotope of neon, ²²₁₀Ne, having ten protons and twelve neutrons; it amounts to about 9% of the element in nature

(physics) The only stable isotope of sodium, ²³₁₁Na, having eleven protons and twelve neutrons

(idiomatic) In hindsight things are obvious that were not obvious from the outset; one is able to evaluate past choices more clearly than at the time of the choice.

(telecommunications, computing) Recommended Standard 232; the standard for serial binary signals between a DTE and a DCE.

(athletics) A sprint race over 200 metres.

A stereotypical characteristic of normal family life; frequently used ironically.

plural of year 2000 problem

The presence of three copies of the 21st chromosome in the karyotype.

(idiomatic, archaic, chiefly US) To leave, particularly quickly or at an advantageous time. / (idiomatic, archaic, chiefly US) To be forced to leave quickly.

(idiomatic, dated, rare, chiefly US) A fictitious place or a generic place that could refer to any location.