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I just told someone on parenting that a baby becomes a toddler when it starts moving around. The question which came back was "what age does a toddler stop being a toddler?".

That got me searching, and I found at least one reference that said "Toddlers are babies from one year to four years of age".

I'd never consider a four-year-old as a baby. Is this just me, or a geographical difference?

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migrated from english.stackexchange.com Nov 28 '11 at 18:49

This question came from our site for linguists, etymologists, and serious English language enthusiasts.

To some degree, a toddler is a type of baby: specifically, a baby that has learned to walk. (Not just move around: a crawling baby is not yet a toddler.) There does come a point, though, when a child can be called a toddler, but not really a baby. I'm not sure when that point is - maybe when the toddler has learned to speak in a semi-understandable fashion? –  Martha Nov 28 '11 at 15:03
@JeffAtwood: what gives? How was this question off-topic for EL&U? –  Mr. Shiny and New 安宇 Nov 28 '11 at 19:21
@Martha: I'd put the cutoff for "baby" at toilet training. A toddler in diapers is still a baby. A toddler who yells for you to come wipe is no longer a baby. –  JPmiaou Nov 28 '11 at 22:13
this question belongs on parenting; you might as well argue that specific questions about programming terminology belong on english.se instead of Stack Overflow or Programmers, which is completely nonsensical. I will also add that as a parent this is EXACTLY the question my wife and I asked each other about our child -- when does he stop being a baby and become a toddler? It's the only time it ever came up in our lives. We even had debates about it. –  Jeff Atwood Nov 30 '11 at 19:41
I'd just like to clarify something. @JeffAtwood seems to be taking the question from the first paragraph and believes that that is the question, whereas I'm reading that that as a starting point that led to the question "Can a toddler be simultaneously categorized as a baby?" (i.e. Jeff is reading this as when someone moves from C to D in this chart I just made whereas I'm reading it as whether B exists or not). Benjol, would you mind clarifying this? –  waiwai933 Dec 3 '11 at 7:20

7 Answers 7

I don't think there's a universal definition.

Going by the American Academy of Pediatrics:

  • Baby = 0 - 1 year (Sometimes called "Infant" in other sources)
  • Toddler = 1 - 3 years (Some still consider young toddlers to be 'babies')
  • Preschooler = 3 - 5 years
  • Gradeschooler = 5 - 12 years (Sometimes called 'school age' in other sources)

Clothing manufacturers, on the other hand, consider toddlers from 2 - 4, which is why you see 2T - 4T clothing sizes.

I would say the real test is based on developmental milestones rather than age. A child is a toddler once they begin walking/toddling around, and ceases to be a toddler when they have met a number of milestones such as communication, toilet training, and motor skills.

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Good citation. Not sure why the other answers are being upvoted when they are little more than "here's what I think.." –  Jeff Atwood Nov 28 '11 at 18:49
There is also a size 5T (and 5, which AFAICT is synonymous). –  msh210 Nov 28 '11 at 19:26
As near as I can tell, the T in children's clothing sizes indicates diaper access. I'd expect crotch snaps on size 4T overalls, but not on size 4 overalls. Of course, like clothing sizes in general, it all depends highly on the manufacturer. –  JPmiaou Nov 28 '11 at 22:10
+1 for the link, and for "the real test is based on developmental milestones". The milestones are far more important than chronological age, considering how much variance there is in children meeting those milestones. –  Beofett Nov 30 '11 at 20:10
@Bryce: Not necessarily - I've seen preschools that don't require it, and kids in preschool who haven't mastered it. But as I mentioned, toilet training is indeed one of the milestones commonly factored in to the toddler/preschool distinctions. –  Lynn Jun 26 '12 at 4:20
  • Infant: 0 - 1
  • Toddler: 1 - 3
  • Pre-Schooler: > 3

While it can vary to some extent based on a child's development; the above is fairly common across the US.

Baby on the other hand is an umbrella term and has no distinct cut off point.

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+1 for umbrella term. Didn't know that. –  Terry LiYifeng Nov 28 '11 at 16:17

Neither toddler nor baby are defined strictly according to age. I would take them to be mutually exclusive, using the definition that a baby is a very young child who has not learnt to walk while a toddler is a young child who has just learnt to walk.

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I would make this distinction between infant and toddler, not between baby and toddler. In my lexicon, an 18-month-old is still definitely a baby, while also definitely being a toddler. –  Martha Nov 28 '11 at 17:02
@martha OK cool. –  Jasper Loy Nov 28 '11 at 17:30
@Martha, this may be a UK/US difference - in the UK the first two years of school are "infants" (or were back in my day, which is admittedly an increasingly long time ago...) –  Benjol Nov 28 '11 at 20:57

The term Toddler is pretty definitive and self defining. "Baby" is much more ambiguous, and can be applied over a range of ages, so yes, they certainly can overlap. I don't consider a four year old a baby either, but I know an almost two who is very much a toddler (busily running everywhere) but who is typically referred to as baby.

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They are definitely not mutually exclusive in at least one instance: when referring to "the baby" (of the family), you are referring to the youngest child, regardless of age. In that sense, "the baby" might be a toddler or even a child or teenager.

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Very good point. A lot of times the "cutoff point" for no longer being called a baby is when they get a younger sibling, or maybe cousin. –  Karl Bielefeldt Nov 29 '11 at 4:19

The terms 'baby' and 'toddler' would not be used of a child simultaneously but because of their vagueness might overlap if applied logically. Some sources give definitions by age that do not overlap, but that is an artificial division.

  • a baby (or synonymously an infant) is a child that has just been born and cannot yet talk (incidentally to around 1 year old when they start to talk)
  • a toddler is a child that has just learned to walk (and this incidentally occurs around 1 year of age)

The upper limit between a toddler and just a very young child is much vaguer, I think of it as literally when the child is well-balanced (that is not 'toddling' any more). A four year old doesn't seem to be a toddler any more but a three year old might be. Even a two year could get away with not being a toddler and instead just a very young child.

But despite the logical fact that one might be able to talk but not yet able to walk or walk and not talk (in the varying ways that abilities develop in a child), one would be hard pressed to label a child both a baby and a toddler. If you can walk, you're not a baby any more, you're a toddler. If you can speak but can't yet walk, you'd probably still be labeled a baby (though maybe not an infant).

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I disagree that "baby" is synonymous with "infant". Our 1 year old toddler is still a baby, but definitely not an infant. "Infant" is a subset of "baby". –  Beofett Nov 30 '11 at 20:07
I disagree about "infant = baby" too. On this site, our definition of "infant" is roughly the period of 3-12 months of age. –  Torben Gundtofte-Bruun Feb 28 '13 at 6:38

I think in common usage, a toddler can be baby that can walk or a young child. A baby becomes a toddler when they can walk, but you can still call them a baby until they are maybe two years old. You can call them a toddler until they turn 4.

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