Wurdahuzdą: Proto-Germanic dictionary — *bat- Scott K. Shay Wardja Press https://protogermanic.org/pgmc_bat

Single-entry extract from the dictionary. Cross-references to other entries point to their identifiers in the full dictionary.
bat- ˈbɑt ᛒᚨᛏ-
stem good, favorable, beneficial benefit, advantage; improvement From Proto-Indo-European bʰód-, an o-grade form of root *bʰed- (‘to improve, make better’). It is a lexical stem mainly reflected in the suppletive comparative adverb/adjective *batiz ‘better’ and in secondary nominal and verbal derivatives. The reconstruction of an independent positive adjective **bataz (‘good’) or a neuter s-stem **bataz ‘benefit’ is uncertain and probably unnecessary; the evidence is better explained by assuming a bound stem *bat- to which various derivational suffixes were attached (Lloyd & Springer 1988-2014). The comparative *batiz reflects *bat- + the comparative suffix *-iz. West Germanic adverbial forms such as Old High German baz and Old Saxon bat(t) are best explained from early loss of the comparative ending in short-stemmed *batiz, producing West Germanic *bat (as compared to the expected *bati-), with later dialectal differences depending on the chronology of i-umlaut and analogical leveling.