from the GNU version of the Collaborative International Dictionary of English
- adv. In an able manner; with great ability.
from The Century Dictionary and Cyclopedia
- In an able manner; with ability.
- The termination of adverbs from adjectives in -able.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adv. with competence; in a competent capable manner
From Middle English able + -ly (Wiktionary)