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Upper Bound
A plausible upper limit to the true value of a quantity, usually not a true statistical confidence limit.
Upper Control Arm
The control arm that extends downward from the frame of the vehicle to connect with the axle.
Upper Frequency Cutoff
The highest frequency a circuit can pass.
Upper Quartile
The 75th percentile, calculated by ordering the data from smallest to largest and finding the value which lies 75% of the way up through the data.
Upper Sideband
All of the sum frequencies above the carrier.
UPS
A type of power supply designed to support the load for specified periods when the line varies outside specified limits.
upsilon
A letter of the Greek alphabet.
Upstream Face
The side of a dam that is against the water.
Upwind
The direction from which the wind is blowing. Also the windward side of an object.