A knot can be defined as an embedded circle in $3$-dimensional Euclidean space or in the $3$-sphere $S^3$. There is also a notion of a knot in higher dimensions: an $n$-knot is an embedding of the $n$-sphere into $m$-dimensional Euclidean space where $m>n$.
For $k>3$, is an embedded circle in $k$-dimensional Euclidean space a knot?