Definition of "verily"

When Jesus had thus said, he was troubled in spirit, and testified, and said, Verily, verily, I say unto you, that one of you shall betray me.

1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], John 13:21

He would weep for hours together, and I verily believe that to the very end this spoilt child of life thought his weak tears in some way efficacious.

1898, H.G. Wells, The War of the Worlds, London: William Heinemann, page 218

Are there three or four pleasing poems and are all the rest put in to fill up the book? Nay. verily! The poems in this collection are those that children love.

1904, Mary Elizabeth Burt, Poems That Every Child Should Know, Preface