What is the X in X-mas?
masc. proper name, from Hebrew, literally "watchful," from stem of 'ur "to awake, to rouse oneself."
citizen; wakeful. (1.) A Tekoite, one of David's thirty warriors (2 Sam. 23:26). (2.) An Ithrite, also one of David's heroes (2 Sam. 23:38). (3.) A Jairite and priest, a royal chaplain (2 Sam. 20:26) or confidential adviser (comp. 2 Sam. 8:18; 1 Chr. 18:17).
U.S.-U.K.-Netherlands satellite launched in 1983 that was the first space observatory to map the entire sky at infrared wavelengths.