Imagine a word used to refer to oneself in the plural; sort of a we-meets-ourselves word. Today, etymologists write the word *s(w)e-. This Proto-Indo-European word gave birth to a fascinating and diverse collection of words that all relate back to the idea of we/ourselves.
The word self came to us through Proto-Germanic back when folks were speaking Old English. Some time during its stay in Germanic languages it appears to have lost its plural, inclusive nature.
Another word from this source is secret, which appeared in English in the 1300s, through Latin words meaning private, set apart, withdrawn, or one one’s own.
Sullen made its way to English through Anglo-French. Initially meaning by oneself, alone (in Middle English), sullen didn’t pick up the meaning morose until the late 1300s.
The word swami appeared in English in the 1700s through Hindi. Swami, now meaning Hindu religious teacher, originally meant one’s own or our own master.
Sibling came to us via Proto-Germanic and Old English. Linguists consider sibling an “enlargement” of the root *s(w)e.
And though they appear nothing like their relatives, the words idiot & idiom also came from *s(w)e-. Born of the idea that folks who couldn’t function in society due to apparent lack of mental ability tended to stay to themselves, idiot came to English in the early 1300s through Latin & Old French. An idiom is a figure of speech peculiar to a particular group of people. Idiom came to English through Greek & Latin in the 1500s. The fact that we cling to our idioms as something that defines us appears to have contributed to the existence of this word
All from a little word meaning we/ourselves.
I’d love to know which of these word-siblings you found most surprising. Fee free to use the comments section for such commentary.