So FTP is older than the standardisation of byte size :-)
What’s a nibble of a byte is 8bits
"The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used.[4][5][6][7] The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words of 12, 18, 24, 30, 36, 48, or 60 bits, corresponding to 2, 3, 4, 5, 6, 8, or 10 six-bit bytes. In this era, bit groupings in the instruction stream were often referred to as syllables[a] or slab, before the term byte became common."
If you want to be specific, you could say "octet" to describe a set of 8 bits.
I was curious and searched HN and found this 2012 comment explaining octet is essentially an anachronism, as bytes have been standardized at 8 bits: https://news.ycombinator.com/item?id=4649528 . Feeling old!
I see it used (and use it myself) from time to time in contexts where you want to differentiate between 7/8/9-bit bytes, mostly when working with embedded/low-level software.
Commonly, the word octet is used to refer to IP addresses, and the permission octets of files in nix systems.
> nybble: /nib´l/, nibble, n.
^---- see that word over here?There are differing sizes for bytes. This isn't so common, anymore, but that was the point being made.
> What’s a nibble of a byte is 8bits
A nibble is 4 bits not 8 bits.