[Old English self.]
Many words incorporating self- exist in English, nearly all of them hyphenated. They fall into two broad groups, though the boundary between them is indistinct.
One group has the sense of some action or condition by, for, or in relation to the agent: self-adhesive, self-appointed, self-assembly, self-defence, self-hatred, self-pity, self-propelled, self-respect, self-service.
The other group has a sense of acting automatically or autonomously, by itself or oneself: self-sealing, self-acting, self-closing, self-fulfilling, self-regulating, self-starting.