blue devil

noun

1

blue devils plural : low spirits : despondency, melancholy

2

a

: a common blue-rayed aster (Aster lowrieanus) of the eastern U.S.

b

: blueweed sense 1

3

a

: either of two Australian percoid fishes (Paraplesiops gigas and P. meleagris) brightly marked with light blue dots

b

: a small brilliantly marked blue fish (Pomacentrus fuscus) of the West Indies

Word History

First Known Use

1756, in the meaning defined at sense 1

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!