The word "octet" is absolutely the kibibyte of "bits in a byte".

From https://archive.org/details/byte-magazine-1977-02/page/n145/...:

“A byte was described as consisting of any number of parallel bits from one to six. Thus a byte was assumed to have a length appropriate for the occasion. Its first use was in the context of the input-output equipment of the 1950s, which handled six bits at a time.”

"byte" doesn't even remotely resemble any decimal prefix, so it's okay. The problem is that prefixes "kilo", "mega", etc. are supposed to be decimal prefixes, but are used as binary. And what's worse, they aren't used consistently, sometimes they really mean decimal magnitudes, sometimes they don't.