Definition: To confront a problem head on, right away, verses sitting back and waiting for it to resolve itself or for another person to tackle it. “Grab the bull by the horns” is also a very similar idiom commonly used.
Origins: The exact origins of this phrase is unknown. Christine Ammer stated that it originated in bullfighting around 1800. The “term most likely alludes to grasping a safely tethered bull, not one the metador is fighting in the ring.” However, Tim Bowen argued that the idiom’s origins is actually from the American West. Instead of bullfighting, it found its roots in rodeos where it was common for ranchers and cowhands to attempt their luck at steer wrestling. Bowen asserts that the only way to control and bring down a steer (young bull) was to grab it by the horns. If a person tried to grab anywhere else, they stood the risk of getting bashed by the horns. Regardless of the exact origins, there is one thing I know for sure. It is a bad idea to grab a bull by its horns in just your bra . . . even in a Maidenform bra!
Tim Bowen, “Phrase of the week: to take the bull by the horns,” onestopenglish.com.
Ammer, Christine. The American Heritage Dictionary of Idioms. Boston: Houghton Mifflin Company, 1997, 639.