imbrication n.

mid-15c., nebule "a cloud, mist," from Latin nebula, plural nebulae, "mist, vapor, fog, smoke, exhalation," figuratively "darkness, obscurity," from PIE root *nebh- "cloud."

Re-borrowed from Latin 1660s in sense of "cataracts in the eye;" astronomical meaning "luminous cloud-like patch in the heavens" is from c. 1730. As early as Herschel (1802) astronomers realized that some nebulae were star clusters, but the certain distinction of relatively nearby cosmic gas clouds from distant galaxies (as these are now properly called) was not made until the 1920s, when the latter were resolved into individual stars (and nebulae) using the new 100-inch Mt. Wilson telescope.

"to lay one over another" (as shingles, etc.), 1704 (implied in imbricated), from Latin imbricatus "covered with tiles," past participle of imbricare "to cover with rain tiles" (see imbrication). As an adjective from 1650s. Related: Imbricated; imbricating.

early 15c., "to keep wet; to soak, saturate;" also figuratively "to cause to absorb" (feelings, opinions, etc.), from Latin imbuere "moisten, wet, soak, saturate," figuratively "to fill; to taint," a word of uncertain origin, perhaps from the same root as imbrication. Compare also Old French embu, past participle of emboivre, from Latin imbibere "drink in, soak in" (see imbibe), which might have influenced the English word. Related: Imbued; imbuing.