Doesn't that depend on what species you are talking about ... ?
An 80-120 cm Antaresia maculosa would be a tad large to be called juvenile :? ... so too would an 80-120 cm Acanthophis antarcticus :shock: , or Tiliqua scincoides, or Chelodina longicollis ... :roll:
Neonate = Hatchling
Juvenile/Subadult = are both arbitary, but generally refer to specimens past the first slough that are sexually immature
Yearling = an artifice coined by herpetoculturalists looking for a tag to sell against - older than 1 year but not yet sexually mature might be appropriate
Adult = any sexually mature (in the biological sense) specimen
Not that I wouldn't mind getting my hands on a 120cm "juvenile" Acanthophis spp. mind you ... ;-) :lol: