bucket upper pivot pin

upper hitch pin

upper pivot pin

upper ridge (upper-level ridge)

upper trough (upper-level trough)

upper-air chart (upper-level charty)

water diversion from the upper Yangtze River in the south to the upper Yellow River in the north

cotter pin retaining pin

gudgeon pin [= crosshead pin]

pin-for-pin

pin-to-pin leakage

pin-to-pin reducer

1221 upper working face

2×2 Upper Triangular Operator Matrixes

3-D upper-limb forces

95% Upper confidence limit

a landslide dam located in the upper-reach of Yell

Aberdeen Upper Reservoir

accepted upper limit