late 14c., risere, "rebel, insurgent, one who rises in revolt," agent noun from rise (v.). Meaning "one who rises" (from bed, in a certain manner) is from mid-15c. Meaning "upright face of a stair-step" is by 1738.
Entries linking to riser
Middle English risen, from Old English risan "to rise from sleep, get out of bed; stand up, rise to one's feet; get up from table; rise together; be fit, be proper" (typically gerisan, arisan; a class I strong verb; past tense ras, past participle risen), from Proto-Germanic *us-rīsanan "to go up" (source also of Old Norse risa, Old Saxon risan, Old Frisian risa, "to rise; arise, happen," Gothic urreisan "to rise," Old High German risan "to rise, flow," German reisen "to travel," originally "to rise for a journey"). OED writes, "No related terms have been traced outside of Teutonic"; Boutkan suggests an origin in a lost European substrate language.
From late 12c. as "to rise from the dead," also "rebel, revolt, stand up in opposition." It is attested from c. 1200 in the senses of "move from a lower to a higher position, move upward; increase in number or amount; rise in fortune, prosper; become prominent;" also, of heavenly bodies, "appear above the horizon." To rise and shine "get up, get out of bed" is by 1916 (earlier it was a religious expression). Of seas, rivers, etc., "increase in height," c. 1300.
The meaning "come into existence, originate; result (from)" is by mid-13c. From early 14c. as "occur, happen, come to pass; take place." From 1540s of sound, "ascend in pitch." Also from 1540s of dough. It seems not to have been used of heat or temperature in Middle English; that sense may have developed from the use of the verb in reference to the behavior of fluid in a thermometer or barometer (1650s). Related to raise (v.). Related: Rose; risen.
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he's usually a late riser