cross-staff
[ kraws-staf, -stahf, kros- ]
/ ˈkrɔsˌstæf, -ˌstɑf, ˈkrɒs- /
noun, plural cross-staffs, cross-staves. Astronomy.
an instrument for measuring the angle of elevation of heavenly bodies, consisting of a calibrated staff with another shorter staff perpendicular to and sliding on it.
Also called
forestaff,
Jacob's staff.
Origin of cross-staff
1400–50, for an earlier sense; late Middle English