for *most* intensive purposes

an important linguistic concept is the eggcorn. an eggcorn is a word or phrase that is incorrect but is rooted in plausible sounds or reasoning. "eggcorn" itself is a reference to the common mispronunciation of the word acorn - with no official name for this phenomenon, this example became eponymous.

causes of eggcorns can vary but commonly include folk etymology ("preying" mantis), hypercorrection ("languistics"), and accounting for obscure or archaic words ("baited breath" to replace "bated breath").

eggcorns are subtly different from malapropisms, which are seen as erroneous uses of words or phrases, usually with nonsensical or comical results, e.g. mishearing song lyrics (electric boobs), confusing idioms ("moo point"), misusing big words)

for a great collection of eggcorns check out the eggcorn database. dont look too closely though, as this is a good spot for post ideas ;-)