Let $T = (X, \mathcal{T})$ be a D1106: Topological space such that

(i)	$\mathcal{D} = \mathcal{D}(T)$ is the D3111: Set of topologically dense sets in $T$

The density of $T$ is the D15: Set cardinality \begin{equation} \inf_{D \in \mathcal{D}} |D| \end{equation}