a setting of the lens aperture on a camera calibrated photometrically and assigned a T-number
T-stop in American English
(ˈtiˌstɑp)
noun
Photography
a camera lens aperture setting calibrated to a T number
Word origin
[1955–60]This word is first recorded in the period 1955–60. Other words that entered Englishat around the same time include: backgrounder, geodesic dome, life-support, new wave, rite of passage