What's your definition of these (and any others you want to add)?

I think of newborn as up to 12 weeks, which is also when I stop using weeks and start using months

I think of baby as 3m, up to 12, maybe 18m

Toddler as 12 or 18m up to around 4 (18m is when I stop using months lol)

I think of preschooler as 4-5.

What about you?