Etymology
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relationship (n.)

1640s, "sense or state of being related" by kindred, affinity, or other alliance, from relation + -ship. Specifically of romantic or sexual intimacy by 1944.

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marital (adj.)

"of or pertaining to a husband, or to marriage as it pertains to the husband," hence, more broadly, "pertaining to or relating to marriage, matrimonial," c. 1600, from French maritale and directly from Latin maritalis "of or belonging to married people," from maritus "married man, husband," which is of uncertain origin (see marry (v.)).

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premarital (adj.)

also pre-marital, "done or occurring before marriage," 1863, from pre- "before" + marital. Phrase pre-marital sex attested from 1953.

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extramarital (adj.)

also extra-marital, "occurring outside marriage," by 1844, from extra- + marital.

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interrelationship (n.)

also inter-relationship, "state of being interrelated," 1841, from inter- "between" + relationship.

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rebound (n.)

mid-15c. as "a rejoinder, a reply" (a sense now archaic or obsolete); 1520s, "the return or bounding back of something after striking, act of flying back on collision with another body" in reference to a ball, from rebound (v.); rebounding in this sense is from late 14c.

In modern sports, from 1917 in ice hockey, 1920 in basketball. Transferred and figurative senses from 1560s; the meaning "period of reaction or renewed activity after disturbance" is from 1570s, hence "during a period of reaction after the end of a romantic or marital relationship" (1859).

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seven-year itch (n.)

1899, American English, some sort of skin condition (sometimes identified with poison ivy infection) that either lasts seven years or returns every seven years. Jocular use for "urge to stray from marital fidelity" is attested from 1952, as the title of the Broadway play (made into a film, 1955) by George Axelrod (1922-2003), in which the lead male character reads an article describing the high number of men have extra-marital affairs after seven years of marriage.

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Hindi (adj.)

1825, from Hind "India" (see Hindu) + -i, suffix expressing relationship. As the name of a modern language of India, 1880.

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kinship (n.)

by 1764, from kin + -ship. Relationship covers the same sense but is a hybrid.

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gesellschaft (n.)

1887, "social relationship based on duty to society or an organization," from German Gesellschaft, from geselle "companion" + -schaft "-ship."

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