The adverb ahold, which usually follows some form of the verb get,is a casual American variant of hold. It has no special meanings of its own. Ahold poses no problem in informal speech and writing, but it might be considered out of place in more formal contexts, where it always bears replacement with hold.
Ahold appears occasionally in Canadian English. It is almost nonexistent in varieties of English from outside North America.
Examples
Most major American publications avoid ahold, but the word sometimes appears in quoted speech—for example:
“If it wasn’t for him, I don’t know where I’d be today. He caught ahold of me and dragged me off,” said O’Hagan. [Chicago Sun-Times]
Fauria said, “Emotions get ahold of you sometimes. It’s how you answer.” [Los Angeles Times]
In other contexts, most writers use hold where ahold might appear in casual speech—for example:
However, electricity is not the only crucial ingredient that they have been struggling to get hold of. [BBC News]
My daughter’s gotten hold of my wife’s iPhone. [Wall Street Journal]
Maybe someone gets hold of the computer that causes things to come to life and uses it for nefarious purposes. [Wired]