underground

a.地下的；秘密的 n.地下铁路；地下组织

undercharge, underclothes, undercoat, undercover, undercurrent, undercut, underdeveloped, underdog, underdone, underestimate, underexpose, underexposure, underfed, underfelt, underfloor, underfoot, undergarment, undergird, undergo, undergraduate, undergrowth, underhand, underhanded, underlay, underlie, underline, underling, underlying, undermanned, undermentioned, undermine, undermined, underneath, undernourished, undernourishment, underpants, underpass, underpay, underpin, underplay,