One who aims; one who is responsible for aiming.(noun)
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Use "aimer" in a sentence
"By the way, I have to admit that I had to use google to find out that the Kinski/Romy picture is from L'import c'est d'aimer aka Nachtblende/The Most Important Thing is to Love from 1975."
"On my morning communte I was cut off by a vehicle aimer who was merging into a bus/cycling lane while texting on his popular brand of PDA."
"There they discover that the wireless operator, pilot and bomb aimer are dead."