1. Of or belonging to the anatomical substance called nerve, _e. g._ the
"nervous system," "nervous sheaths," "nervous particles," &c.
2. A predomination of the nervous system, when it is unusually active or
highly developed, which is what we mean in speaking of a "nervous
temperament," "a nervous person," &c.
3. Certain functional disorders of the nervous system are so termed, and
in this sense we speak of "nervous people," "nervous complaints," and so
forth.
4. Nervous is also used, more poetically than correctly, to signify
_muscular_, and as synonymous with brawny, sinewy, &c., thus conveying
an idea of strength and vigour. But _nerve_ is not _muscle_, therefore
this inaccurate use of the word, though sanctioned by some good old
writers, must cease.
5. Nervous, in speaking of a part of the body, signifies a part in which
there are many nerves, or much nervous matter, or which is endowed with
extra sensibility.
These are the various ideas commonly attached to the word _nervous_.
They are too many for the word to be a closely accurate one, but we must
take them, not make them. We can, however, avoid the future inaccurate
use of the term alluded to in explanation 4., and all the metaphorical
derivations thereof, such as a "nervous style of writing," &c., and
adhere to those two significations which are physiologically and
pathologically correct, and which are obviously derivable from the
several meanings and explanations above enumerated, viz.--