mediocrity n. 平庸，碌碌无为(mediocre abilities or attainment)
[例]Grateful as we are for these splendid books, they remain isolated examples of excellence in a literature of mediocrity.
melancholy adj. 忧郁的(depressed);令人悲伤的(causing depression)
[记]词根记忆：melan(黑色)+chol(=bile胆汁)+y→胆汁发黑→忧郁的
menial adj. 仆人的，卑微的(of servants;humble);n. 家仆(a domestic servant)
[例]Although Ms. Brown found some of her duties to be menial, her supervision of forty workers was a considerable responsibility.
[同]subservient, obsequious, servile, slavish
mercenary adj. 唯利是图的(acting merely for money);n. 雇佣兵(a professional soldier hired to serve in a foreign army for money)
[记]词根记忆：mercen(工资)+ary→只为了工钱的→唯利是图的
meretricious adj. 华而不实的，俗艳的(tawdrily and falsely attractive)
[记]来自meretrix(妓女)
meritorious adj. 值得赞赏的(deserving praise and esteem)
[记]merit(优点，长处)+orious(多…的)→长处很多→值得赞赏的
mesmerize v. 对…催眠(to hypnotize);使入迷，迷住(to fascinate)
metabolic adj. 新陈代谢的(of, relating to, or based on metabolism)
[记]来自metabol(y)(新陈代谢)+ic→新陈代谢的
[例]When trees go dormant in winter, the procedure is anything but sleepy: it is an active metabolic process that changes the plant radically.
metamorphose v. 变形(to change into another form)
[记]词根记忆：meta(变化)+morph(形状)+ose→变形
