word - Additions & Twists

Start with a word.
For each line below, add one letter to the last word, then anagram, to get a word that means:

• pitch


• fleet


• slowly


• anent


• public


• adverse

What word did I start as and what words did I become?

_{Part of a metapuzzles entry: I, for one, welcome our new ...}

Answer

The word you started with was

AT

The sequence is as follows:

TAR DART TARDO TOWARD OUTWARD UNTOWARD

This matches up with the title because

AT also stands for "Additions & Twists" (thanks @BeastlyGerbil)