The words boar, boer, bore sound the same but have different meanings and spellings. Why do boar, boer, bore sound the same even though they are completely different words?
The answer is simple: boar, boer, bore are homophones of the English language.
An uncastrated male pig.
The adult male of any of several mammals, such as the beaver, raccoon, or guinea pig.
The wild boar.
A Dutch colonist or descendant of a Dutch colonist in South Africa.
A drilling tool.
To make a hole in or through, with or as if with a drill.
To form (a tunnel, for example) by drilling, digging, or burrowing.
To make a hole in or through something with or as if with a drill: "three types of protein that enable the cells to bore in and out of blood vessels” ( Elisabeth Rosenthal).
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.