(law) A canon of construction under which the questionable meaning of a doubtful word can be derived from its association with other words.
Foster v Diphwys Casson (1887) 18 QBD 428, involved a statute which stated that explosives taken into a mine must be in a "case or canister". Here the defendant used a cloth bag. The courts had to consider whether a cloth bag was within the definition. Under noscitur a sociis, it was held that the bag could not have been within the statutory definition, because parliament's intention was referring to a case or container of the same strength as a canister.