1. Synthetic polyamide comprising one or more of the following compounds:a) a compound having at least one sterically hindered amino group, �hereinafter referred to as compounds a)!; orb) a trimesinic acid trialkylamide, at least one alkyl group of which bears at least one free amino and/or alkylamino group �hereinafter referred to as compounds b)!; orc) a trialkylamino-substituted triazine, at least one alkyl group of which carries a free amino and/or alkylamino group �hereinafter referred to as compounds c)!; ord) a dyestuff that is free of sulphonic acid groups and contains at least one group that is reactive to a hydroxy and/or amino group �hereinafter referred to as compounds d)!; ore) a synthetic polyamide containing at least one group that is reactive with a hydroxy and/or amino group �hereinafter referred to as compounds e)!.