Learn how to say Cardioids correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word cardioid:
a heart-shaped curve traced by a point on the circumference of a circle as it rolls around another identical circle.
(also cardioid microphone) a directional microphone with a heart-shaped pattern of sensitivity.
of the shape of a cardioid.
mid 18th century: from Greek kardioeidēs ‘heart-shaped’, from kardia ‘heart’ + eidos ‘form’