casually

Etymology

From Middle English casually, casuelly, casuali, casuely, equivalent to casual + -ly.

adv

1. In a casual manner.
   A small minority, mainly strangers, would look long at her in casually passing by, and grow momentarily fascinated by her freshness, and wonder if they would ever see her again: but to almost everybody she was a fine and picturesque country girl, and no more. 1891, Thomas Hardy, Tess of the d'Urbervilles, volume 1, London: James R. Osgood, McIlvaine and Co., page 21
   The detective kept them in view. He made his way casually along the inside of the shelter until he reached an open scuttle close to where the two men were standing talking. Eavesdropping was not a thing Larard would have practised from choice, but there were times when, in the public interest, he had to do it, and this was one of them. 1928, Lawrence R. Bourne, chapter 7, in Well Tackled!
   He wore his strange and colourful clothes as if for inspection by a lesser being: condescendingly, casually. 1974, John Boorman, Zardoz, London: Pan Books, page 10