assay

Concise Oxford English Dictionary © 2008 Oxford University Press:
assay /əˈseɪ, ˈaseɪ/

▶noun

• 1 the testing of a metal or ore to determine its ingredients and quality.

• 2 a procedure for measuring the biochemical or immunological activity of a sample.

▶verb

• 1 carry out an assay on.

• 2 archaic attempt.

– derivatives
assayer noun.

– origin ME: from OFr. assai (n.), assaier (v.), var. of essai ‘trial’, essayer (see essay).