"characterized by great effort," 1599, from L. strenuus "active, vigorous, keen." Probably cognate with Gk. strenes, strenos "keen, strong," strenos "arrogance, eager desire," O.E. stierne "hard, severe, keen" (see stern (adj.)). Mocked by Ben Jonson as a pedantic neologism
in "Poetaster" (1601). Sense of "requiring much energy" is first recorded 1671.