most・mostly
generally
more or less
roughly・approximately
in the first place
Structure
- だいたい + の + Noun
- だいたい + Phrase
- だいたい + Number/Degree
[だいたい is very often used with words like ころ（ごろ）, くらい（ぐらい）, etc.]
[だいたい is also often used when criticizing someone’s behavior, meaning “in the first place, to begin with”]
[大体だいたい is also a noun meaning “an outline,” “main point,” or “gist”]
[だいたい is very often used with words like ころ（ごろ）, くらい（ぐらい）, etc.]
Does this emphasize the “approximate” part of those other words, or is some other meaning added?
Hey and sorry for the late answer 
Yes, だいたい is used together with those to emphasize that it is not the exact amount, but “more or less” about that much and to make the sentence a bit more casual.
I hope it helps,
Cheers!