Inviscate spiked on May 25th, following the correct spelling of the word by Akash Vukoti, a six-year-old contestant at the Scripps National Spelling Bee. The word, which is defined as "to encase in a sticky substance: make viscid," has been in use in English since the beginning of the 15th century.
Inviscate is from the Late Latin word inviscatus, which is the past participle of inviscare ("to snare as with birdlime"). It is related through its etymology to a couple of other sticky words in English, such as viscid and viscosity.