Noun
lemniscate of Bernoulli (plural lemniscates of Bernoulli)
(mathematics) Any closed curve described by a Cartesian equation of the form
(
x
2
+
y
2
)
2
=
2
a
2
(
x
2
−
y
2
)
{\displaystyle (x^{2}+y^{2})^{2}=2a^{2}(x^{2}-y^{2})}
.