from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Describing one who assents, who agrees.
from the GNU version of the Collaborative International Dictionary of English
- adj. Giving assent; of the nature of assent; complying.
from The Century Dictionary and Cyclopedia
- Giving assent; complying. Savage.
Sorry, no etymologies found.
The last is called by some casuists the refusal assentive.
(Who can read without assentive chuckles his delicious "Lines to a Don!"