from The American Heritage® Dictionary of the English Language, 4th Edition
- adv. Without delay; instantly.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adv. immediately; instantly; without delay
from the GNU version of the Collaborative International Dictionary of English
- adv. Immediately; instantly; at once.
from The Century Dictionary and Cyclopedia
- At the present time; immediately; without delay: as, the party was compelled to plead instanter.
Medieval Latin, from Latin, urgently, from īnstāns, īnstant-, present; see instant.(American Heritage® Dictionary of the English Language, Fourth Edition)