What is the meaning of the word "dull"?

Definitions:

(of business) not active or brisk adjective
- business is dull (or slow)
being or made softer or less loud or clear adjective
- the dull boom of distant breaking waves
blunted in responsiveness or sensibility adjective
- a dull gaze
emitting or reflecting very little light adjective
- a dull glow
lacking in liveliness or animation adjective
- They were so dull at parties.
make dull in appearance verb
- Age had dulled the surface
make dull or blunt verb
- Too much cutting dulls the knife's edge
make less lively or vigorous verb
- Middle age dulled my appetite for travel.
not having a sharp edge or point adjective
- the knife was too dull to be of any use
not keenly felt adjective
- a dull throbbing