pit pony

pony used (esp formerly) underground in a mine to pull heavy loads （尤指旧时的）矿井下运输用的小马.

piracy, piranha, pirate, piratical, piratically, pirouette, Pisa, piscatorial, Piscean, Pisces, piss, pissed, pistachio, piste, pistil, pistol, piston, piston ring, piston-engined, pit, pit-a-pat, pit-a-pat (also pitter-patter), pit-head, pit-prop, pitch, pitch-and-toss, pitch-black, pitch-dark, pitch-pine, pitchblende, pitched, pitcher, pitchfork, piteous, piteously, piteousness, pitfall, pith, pith hat (also `pith helmet), pithily,