Initially
来自Big Physics
early 16th century: from Latin initialis, from initium ‘beginning’, from inire ‘go in’, from in- ‘into’ + ire ‘go’.
wiktionary
initial + -ly
early 16th century: from Latin initialis, from initium ‘beginning’, from inire ‘go in’, from in- ‘into’ + ire ‘go’.
initial + -ly