Tenebrae

noun

Ten·e·brae ˈte-nə-ˌbrā

-ˌbrī,

-ˌbrē

plural in form but singular or plural in construction

: a church service observed during the final part of Holy Week commemorating the sufferings and death of Christ

Word History

Etymology

borrowed from Medieval Latin, "office sung during Holy Week during which candles are extinguished after each psalm," going back to Latin tenebrae (plural) "darkness, obscurity," by dissimilation from *temebrai, going back to Indo-European *temH-s-ro-/*temH-es-ro- (whence also Sanskrit támisrāḥ, plural, "darkness, night," Germanic *þemestra- "dark"—whence Middle Dutch deemster "dark," Old High German dinstar, finstar), adjective derivative from a noun *temH-es- "darkness" — more at temerity

Note: Also most likely related are Old English þēostre, þīestre "dark, gloomy," Old Frisian thiustere, Old Saxon thiustri, assuming that *-ems-, through shift of m to a nasalized semi-vowel and denasalization, became a diphthong *-iu̯-. Old High German finstar (whence Modern German finster) and Middle Dutch vinster probably go back to a shift of *þim- to *fim- (the initial fricative taking on the labial quality of the following m), with later assimilation of m to n before following -st-.