(computing) Initialism of n-key rollover: a keyboard feature that prevents ghosting and blocking.

(organic chemistry) The zwitterion (2S)-3-(1H-imidazol-4-yl)-2-(trimethylammonio)propanoate related to histidine

(attributive) A technique in which the necessary conditions for a state are identified and then a proof that these conditions cannot be satisfied is produced.

(biochemistry) A form of a globin that lacks a heme unit