Definition:

The term mathematically gifted is used to refer to children who have strong math skills. The mathematically gifted kids perform better on spatial, nonverbal reasoning, speed, memory, and mechanical comprehension tests than verbally gifted children do.

Children who are mathematically gifted tend to be able to understand math concepts at younger ages than other children. They are able to understand and manipulate mathematical symbols easily.

See also:
Globally Gifted
Verbally Gifted

Source: Benbow, C.P., & Minor, L.L. (1990). Cognitive profile s of verbally and mathematically precocious students: Implications for identification of the gifted. Gifted Child Quarterly, 34 (1), 21-26.