Meaning:
The phrase go out on a limb has two meanings:
1. Putting yourself in a risky or precarious situation in order to help someone.
2. Taking a wild guess at something.

The Origin Of ‘Go Out On a Limb’
Where does the phrase go out on a limb come from? Its origin might be rooted in tree climbing. How so? Because the word “limb” can refer to the branches of a tree. So if someone climbed a tree and went out onto one of its branches, they would be going out on a limb.
This might also be where the phrase got its “taking a risk” meaning from, because climbing trees can be a dangerous thing to do. Indeed, the branches could break if someone is climbing around on them, or the person could lose their grip and fall. Thus, this potentially hazardous activity might be where the phrase originated from and how it derived the “risky” part of its definition.
Now let’s take a look at how old this expression is. The earliest I could find it in print with a figurative meaning is from the Steubenville Daily Herald newspaper, 1895:
“We can carry the legislature like hanging out a washing. The heft of the fight will be in Hamilton country. If we get the 14 votes of Hamilton we’ve got ’em out on a limb. All we’ve got to do then is shake it or saw it off.”
Since the expression dates back to at least 1895, that means it is 120 years old at minimum.
Example Sentences
- I’m going out on a limb for you here and you aren’t even going to thank me for my help?
- We can’t figure out how our dog managed to get out of our backyard, but if I were to go out on a limb, I would say he probably jumped over the wooden fence.
The quotes that contain these popular sayings are there to give you an idea on how old it is. For example, if a phrase’s first known appearance is in a book from 1855, then you know the phrase it at least that old.