dullish

From Middle English dullissh, equivalent to dull +‎ -ish.

dullish (comparative more dullish, superlative most dullish)

1. Somewhat dull; dull to a degree.
   • 1918 August, Katherine Mansfield [pseudonym; Kathleen Mansfield Murry], “Bliss”, in Bliss and Other Stories, London: Constable & Company, published 1920, →OCLC, page 121:

     Harry said "No.” Voted her dullish, and “cold like all blond women, with a touch, perhaps, of anæmia of the brain.”