In medicine and psychiatry, a “syndrome” can be conceptualized simply as a constellation of phenotypic traits and differences that shows some tendency to be found together in sets of individuals or that, when found together, causes particular sorts of problems. A syndrome may thus comprise a set of morphological, neurological, physiological, behavioral and developmental traits, each of which shows some level of difference from the age- and gender-typical average.

Reference:
Crespi BJ. The hallmarks of autism. Front Psychiatry. 2022 Aug 2;13:937163. doi: 10.3389/fpsyt.2022.937163. PMID: 35982934; PMCID: PMC9379287.