luer, n. — Green’s Dictionary of Slang

luer n.

[proprietory name Luer brand syringe]

(US drugs) a hypodermic syringe.

1936		D. Maurer ‘Argot of the Und. Narcotic Addict’ Pt 1 in AS XI:2 123/2: luer. A hypodermic needle.
1953		Anslinger & Tompkins Traffic In Narcotics 312: leur, luer. A hypodermic needle.
1959		J.E. Schmidt Narcotics Lingo and Lore.