Is it farther or further?
suffix attached to a verb, first attested 1960 with sit-in (which probably was influenced by sit-down strike); used first of protests, extended c.1965 to any gathering.
chemical suffix, usually indicating a neutral substance, antibiotic, vitamin, or hormone; see -ine (2).
Neutral chemical compound: inulin.
Variant of -ine2.
A communal occasion where one does what is indicated: be-in/ lie-in/ love-in/ pray-in (1960s+)