noun, plural fly·bys.
Origin of flyby
1950–55, Americanism; noun use of verb phrase fly by
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
noun plural -bys
a flight past a particular position or target, esp the close approach of a spacecraft to a planet or satellite for investigation of conditions
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012