boon

Etymology 1

From Middle English boon (“prayer”), from Old Norse bón (“prayer, petition”), from Proto-Germanic *bōniz (“supplication”), influenced by boon (“good, favorable”, adj). Doublet of ben; see there for more.

noun

1. A good thing; a blessing or benefit; a thing to be thankful for.
   Finding the dry cave was a boon to the weary travellers.
   Anaesthetics are a great boon to modern surgery.
   Not long ago, it was difficult to produce photographs of tiny creatures with every part in focus. […] A photo processing technique called focus stacking has changed that. Developed as a tool to electronically combine the sharpest bits of multiple digital images, focus stacking is a boon to biologists seeking full focus on a micron scale. 2013 July–August, Catherine Clabby, “Focus on Everything”, in American Scientist, volume 100, number 4, archived from the original on 2013-09-07
2. (archaic) That which is asked or granted as a benefit or favor; a gift or benefaction.
   Every good gift and every perfect boon is from above, coming down from the Father of lights, with whom can be no variation, neither shadow that is cast by turning. 1881, English Revised Version, The New Testament, in the revised version of 1881, with fuller references, Oxford: Oxford University Press, published 1910, James 1:17, page 548
   I gave you life. Can you not return the boon by giving me death, my lord? 1871, James De Mille, The Cryptogram, New York: Harper & Brothers Publishers, →OCLC, page 194, column 2
3. (obsolete) A prayer; petition.
4. (Britain, dialectal) An unpaid service due by a tenant to his lord.

Etymology 2

From Middle English boon, bone, borrowed from Old Northern French boon, from Old French bon (“good”), from Latin bonus (“good”), from Old Latin duonus, dvenos, from Proto-Indo-European *dū- (“to respect”).

adj

1. (now only in boon companion) Gay; merry; jovial; convivial.
   (2) "Everybody's boon companion, / Everybody's chaperon"; (3) "Everybody's boon companion: / Give[s] 'em everything he's got" 1985, Herbert Kretzmer (English lyrics), Les Misérables (musical), "Master of the House," second and third refrains, fifth line
2. (archaic) Kind; bountiful; benign.
3. (obsolete) Good; prosperous.
   boon voyage

Etymology 3

From Middle English bone (“reed, stem, husk”), akin to or alteration of Old English bune (“reed; drinking cup”).

noun

1. The woody portion of flax, separated from the fiber as refuse matter by retting, braking, and scutching.

Etymology 4

noun

1. (slang) Clipping of sheboon.