出典:Wiktionary
From Middle English gladere, from 古期英語 glædra (adj), glador (adverb), comparative of glæd (“glad, shining, bright”). More at glad.
From gladder (“one who makes glad”), or perhaps from Middle English *gladderen, from 古期英語 *gladrian (“to make glad”), equivalent to glad + -er (fequentative suffix).
gladder (三人称単数 現在形 gladders, 現在分詞 gladdering, 過去形および過去分詞形 gladdered)