Definition of pipe for English Language Learners. : 1  a long, hollow tube for carrying water, steam, gas, etc. : 2  a tube with a small bowl at one end that is used for smoking tobacco. : 3  a musical instrument that is in the shape of a tube, has holes along the top, and is played by blowing.
The Blood of Olympus (mentioned) Lupa is the immortal Roman wolf goddess who trains Roman demigods in the ways of Rome. She trains the demigods at the Wolf House, then sends them to Camp Jupiter where they can join the Twelfth Legion.
Wolves as a symbol of lust are ancient, e.g. Roman slang lupa whore, literally she-wolf (preserved in Spanish loba, Italian lupa, French louve). The equation of wolf and prostitute, sexually voracious female persisted into 12c., but by Elizabethan times wolves had become primarily symbolic of male lust.