(topology, algebraic topology) Any of a sequence of numbers, denoted bₙ, which characterise a given topological space K by giving, for each dimension, the number of holes in K of said dimension; (formally) the rank of the nth homology group, Hₙ, of K.

(mathematics) By means of, or in terms of, number theory.

(mathematics, number theory) The branch of number theory in which number-theoretic questions are expressed in terms of properties of algebraic number fields or related objects, and studied using techniques from algebra.

A small marsupial carnivore, Myrmecobius fasciatus, endemic to western Australia, that eats almost exclusively termites.

(graph theory) the number of edges in a maximum matching, often denoted 𝜈=𝜈(G)

(graph theory) the number of vertices in a maximum independent set of a given graph, often denoted as 𝛼=𝛼(G)

(graph theory) the number of vertices in a minimum dominating set of a given graph, often denoted as 𝛾=𝛾(G)

(graph theory) The number of vertices in a minimum vertex cover of a graph, often denoted as 𝜏=𝜏(G).

(graph theory) The number of edges in a minimum edge cover of a graph, often denoted as 𝜌=𝜌(G).

(Britain) Either of a pair of rectangular metal plates bearing an alphanumeric code, fixed to the front and rear of a motor car to show its identity as registered with the DVLA.