Definition

A streak is a disease symptom that appears as a line, mark, smear, or band differentiated by color or texture from its surroundings.

Above: Green streaks on papaya (Carica papaya) petioles, a symptoms of papaya ringspot disease, caused by the plant-pathogenic virus, papaya ringsopt virus.

Etymology. 1768, "to go quickly, to rush, run at full speed," respelling (by association with streak (n.)) of streek "to go quickly" (c.1380), originally "to stretch oneself" (c.1250), a northern M.E. variant of stretch (v.). Streaking "running naked in public" first recorded 1973.