Etymology tree
English dry
Proto-Indo-European *-yōs
Proto-Germanic *-izô
Proto-West Germanic *-iʀō
Proto-Germanic *-ōzô
Proto-West Germanic *-ōʀō
Old English -ra
Middle English -ere
English -er
English drier
From dry + -er (comparative suffix).
Meanings
(comparative, form-of) comparative form of dry: more dry