Research To Date Has Shown: 1  ADHD is a neurobiologic condition whose symptoms are also dependent on the child's environment. 2  A lower level of activity in the parts of the brain that control attention and activity level may be associated with ADHD. 3  ADHD frequently runs in families.
Mosaic (genetics) In genetics, a mosaic (or mosaicism) means the presence of two different genotypes in an individual which developed from a single fertilized egg. As a result, the individual has two or more genetically different cell lines derived from a single zygote. Unusual events in cell division (mitosis).
Chambers 20th Century Dictionary(0.00 / 0 votes)Rate this definition: 1  Mosaic. mÃ¶-zÄâ²ik, n. a kind of work in which designs are formed by small pieces of coloured marble, glass, &c. cemented on a ground of stucco, or inlaid upon metal.âadj. relating to, or composed of, mosaic.âadv. 2  Mosaic.