In heraldry, describing animals or figures shown swimming or moving in opposite directions on a shield or coat of arms.
From counter- + naiant (from Old French nager, 'to swim,' via Latin natare). A technical heraldic term used to describe the positioning of swimming creatures in coat of arms design.
Heraldry has absurdly specific vocabulary—'counternaiant' is used to describe two fish swimming in opposite directions on a coat of arms, a detail that mattered enormously to medieval nobility.
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