冷门lěngmén(～ㄦ{lěngménr})原指赌博时很少有人下注的一门。现比喻很少有人从事的、不时兴的工作、事业等{(of gambling) stake to which few people choose to place a bet; (fig.) profession, trade or branch of learning that receives little attention; rarefied undertaking, programme, etc.}: 过去地质学是～ㄦ。{In the past, geology was a branch of learning that received little attention.}