toxic:  The etymological meaning underlying toxic is of ‘poisoned arrows’. Its ultimate source is Greek tóxon ‘bow’, which also gave English toxophily ‘archery’ . From it was derived toxikós ‘of bows and arrows’, which formed the basis of a noun toxikón ‘poison for putting on arrows’. Latin took this over as toxicum ‘poison’, and the medieval Latin derivative toxicus gave English toxic. => toxophily
1660s, from French toxique and directly from Late Latin toxicus "poisoned," from Latin toxicum "poison," from Greek toxikon (pharmakon) "(poison) for use on arrows," from toxikon, neuter of toxikos "pertaining to arrows or archery," and thus to a bow, from toxon "bow," probably from a Scythian word that also was borrowed into Latin as taxus "yew." Watkins suggests a possible source in Iranian taxša- "bow," from PIE *tekw- "to run, flee." As a noun from 1890.