Bull
Bull turns up in 2 fields: railroad, farming. Here is what it means to the people in each one.
Bull in railroad
A railroad police officer, the special agent who patrols yards and trains for trespassers and thieves.
Railroads employ their own police, special agents with full law enforcement authority on railroad property, and crews and freight hoppers call them bulls. Bulls handle trespassing, cargo theft, vandalism and crossing violations, and they investigate after accidents. To a freight hopper the yard bull is the main worry; to a crew, the bull is the one who shows up when someone is on the tracks.
"Kids on the bridge again by MP 302, call the bull and ask him to run 'em off before somebody gets hurt."
Bull in farming
Showing physiological signs of estrus and a readiness to accept a mate.
A cow or heifer is said to bull when she enters the active phase of estrus and becomes receptive to breeding. Handlers look for physical indicators like restlessness, clear mucus discharge, and standing to be mounted by other cattle. Identifying exactly when a cow begins to bull dictates the timing for successful artificial insemination or pasture breeding.
"Watch that black heifer in the lower pen, she started bulling this morning and needs to be bred tonight."