Deflection

Deflection is an ambiguous term in many sources covering the World War I period, especially British ones owing to the twisted etymology of the word.

Be careful when contemporary British sources use the word "deflection", as it might mean either speed-across or lateral aim-off depending on the context.

When a British source says...	...it means
"Deflection"	(ambiguous)
"Gun Deflection"	Lateral Aim-off
"Sight Deflection"	Lateral Aim-off
"Dumaresq Deflection"	Speed-across