[Jords]

I know what Niamh means. If an adult points at a colour and says this is 'yellow', and it is actually yellow, but the child sees yellow as purple, the child will learn the colour name of purple as yellow and will not know different. Unless you descibe the colour, where the adult will say bright, but the child would say dull.

[Chels]

i've thought about this before!
i've also thought about if people hear the same sounds as you.