excel
Pronunciation: /ɪkˈsɛl, ɛk-/
verb ( excels, excelling, excelled)

Origin:
late Middle English: from Latin excellere, from ex- 'out, beyond' + celsus 'lofty'

Spelling rule
Double the l when adding endings which begin with a vowel to words which end in a vowel plus l (as in travel):