fastly

From Middle English fastly, fastliche, festliche, from Old English fæstlīċe (“firmly, constantly”), from Proto-West Germanic *fastulīkē, from Proto-West Germanic *fastulīkê (“securely, firmly”); equivalent to fast +‎ -ly.

fastly (comparative more fastly, superlative most fastly)

1. In a secure or firm manner; securely

   Synonyms: fast, firmly, securely, tightly

   We tied the rope fastly this time; we didn't want it to get away again.

   • 1843, Thomas Archer, Roderick Dhu, Clan Alpine's Chief, or, the Scottish outlaw:

     Before them was a door which apparently led into the grand apartments; this was fastly secured, but it yielded to their united strength, and they entered a lofty hall, whose concave top was supported by pillars.

From fast +‎ -ly.

fastly (comparative more fastly, superlative most fastly)

1. (nonstandard) quickly
   • 1885, The Missionary Herald of the Baptist Missionary Society, page 162:

     Determined in his death, and chasing him, he ran fastly to the 'Mission House,' and under Mrs. Richardson's bed he was sheltered and saved.

   • 1990, Shailendra Jha, Agricultural labour: present position and problems, legislations, and governmental steps, measures for upliftment:

     This trend continued upto the close of the Second World War, although the price index moved fastly.

   • 2011, Raj Kumar Singh, Contemporary India with Controversial Neighbours, page 264:

     The turn of events moved fastly in Nepal at the close of the century and thereafter as well.