fastly

adverb2

1. •
   In a secure or firm manner; securely

   • We tied the rope fastly this time; we didn't want it to get away again.
2. •
   (nonstandard) quickly

   • Another time, my Mother seeing them come fastly to her house, my brother gave the key of his desk to my sister, bidding her convey the money somewhither; […] — 1661