trepan

n 1 (medical 医) early form of trephine （早期的）环钻, 环锯. 2 (engineering 工) bore for drilling a mine shaft 钻井机.

trembly, tremella, tremendous, tremendously, tremolo, tremor, tremulous, tremulously, trench, trench coat, trenchant, trenchantly, trencher, trencherman, trend, trend-setter, trend-setting, trendily, trendiness, trendy, trephine, trepidation, trespass, trespasser, tress, trestle, trestle-table, trews, tri-, triad, trial, trial run, triangle, triangular, tribal, tribalism, tribe, tribesman, tribulation, tribunal,