没有词源——这是它最特别的一笔。造词人特诺夫自己说，这个词是刻意的无源之水： 不借任何既有词根，只挑了一串听起来像那么回事的音。 一种没人命名过的状态，配了一个没有祖先的词。

It has no etymology — and that is its signature. Tennov said so herself: the word was deliberately rootless, borrowed from no stem, chosen purely for its sound. A state nobody had named, fitted with a word that has no ancestors.

心理学家多萝西·特诺夫研究了十年——数千份问卷、几百例访谈——在 1979 年的 《爱与痴恋》（Love and Limerence）里给这种状态立了案：非自愿的痴迷、 侵入性的念头、对「对方有没有回应」的极端敏感，甜与苦全由不确定性供血。 她的核心论点直到今天还扎人：这不是爱的浓一点，是另一种东西。

学界对概念聚讼多年，词却自己活下来了：OED 首证 1977，Merriam-Webster 在录—— 学者造词转正一族的第五人：化学家、神学家、语文学家、天文学家之后，来了位心理学家。

The psychologist Dorothy Tennov spent a decade on it — thousands of questionnaires, hundreds of interviews — and filed the state in Love and Limerence (1979): involuntary obsession, intrusive thought, exquisite sensitivity to reciprocation, the sweet and the sick both fed by uncertainty. Her central claim still stings: this is not love turned up; it is another thing.

Academia argued for decades; the word simply survived: OED evidence from 1977, Merriam-Webster on board — the fifth member of the scholars’-coinage clan, a psychologist after the chemist, the theologian, the philologist and the astronomer.

中医早把它挂了号：相思病——「害相思」，把痴恋当病症，和特诺夫的思路隔着几百年握手。 网络时代的口语版是「上头」，准确而轻快，少了病历的分量。 「单相思」最接近它的常见形态，但 limerence 的要害不在「单」， 在非自愿：双向的痴恋一样是它，一样停不下来。

Chinese medicine registered it long ago: 相思病, lovesickness — 害相思, to “suffer longing” as an ailment, shaking hands with Tennov across the centuries. The internet’s spoken version is 上头 — accurate, brisk, minus the medical chart. 单相思, one-sided longing, matches its commonest form, but limerence’s crux isn’t the one-sidedness; it is the involuntariness — mutual limerence is limerence all the same, and just as unstoppable.