求一个英文单词 中文意思是 蓝色 'M ' 开头的

表示蓝色的词有:
azure, beryl, blue, cerulean, cobalt, indigo, navy, royal, sapphire, teal, turquoise, ultramarine
没有m开头的.

但如果你查近义词词典找blue的近义词,有melancholy和moody,这是取"忧郁"之义.

介绍你一个最知名的网上英文近义词词典,很有帮助:
http://thesaurus.reference.com

在页面上输入任意一个你所需要的意思的单词,点Search就可以了.
比如你输入blue,就会出现很多组词条,诸如:

Main Entry: blue
Part of Speech: adjective 1
Definition: sad
Synonyms: dejected, depressed, despondent, disconsolate, dismal, dispirited, down-hearted, downcast, fed up*, gloomy, glum, low, melancholy, moody, unhappy, woebegone
Antonyms: gay, happy, joyful, joyous, upbeat

Main Entry: blue
Part of Speech: noun
Definition: color
Synonyms: azure, beryl, cerulean, cobalt, indigo, navy, royal, sapphire, teal, turquoise, ultramarine

......

其中main entry是你输入的单词,part of