adverb
Etymology: Middle English surly, from sur sure + -ly — more at sure
1. : in a sure manner:
a. archaic : safely , securely
he that walketh uprightly walketh surely — Prov 10:9 (Authorized Version)
b.
(1) : with assurance or confidence
people who respond immediately and surely to works of art — Clive Bell
(2) : without doubt : certainly , undoubtedly
the tremendous growth that is surely ahead in this country — C.F.Craig
c. obsolete : in a faithful manner : loyally
that I may surely keep mine oath — Shakespeare
2. : assuredly , indeed , really — often used as an interjection or intensive or to qualify a statement