Entry 2 senses · 2 variants Webster, 1913 Grimly /grĭm'-lē/ · Grim·ly · IPA /ˈɡɹɪmli/ a. adv. 01 a. Grim; hideous; stern. 1. Grim; hideous; stern.[R.] “In glided Margaret's grimly ghost, And stood at William's feet.” — D. Mallet. 02 adv. In a grim manner; fiercely. 1. In a grim manner; fiercely.