Definition of paraffin test in US English:

paraffin test

noun

  • A forensic test to indicate whether a person has recently fired a gun, in which the person's hand is coated in hot paraffin wax which cools and sets and is peeled off and tested for the presence of residue from the gun.

Origin

1930s; earliest use found in The Washington Post. Probably after American Spanish; use of the test in Mexico City is reported from 1931.