pinpoint n.

late Old English pinn "peg or bolt of wood or metal used to hold things in place or fasten them together," from Proto-Germanic *penn- "jutting point or peak" (source also of Old Saxon pin "peg," Old Norse pinni "peg, tack," Middle Dutch pin "pin, peg," Old High German pfinn, German Pinne "pin, tack") from Latin pinna "a feather, plume;" in plural "a wing;" also "fin, scoop of a water wheel;" also "a pinnacle; a promontory, cape; battlement" (as in Luke iv.9 in Vulgate) and so applied to "points" of various sorts, from PIE root *pet- "to rush, to fly."

De Vaan and Watkins say Latin pinna is a derivative of penna, literally "feather" (see pen (n.1)); older theories regarded pinna as a separate word from a root meaning "sharp point." The Latin word also was borrowed in Celtic: Irish pinne "a pin, peg, spigot;" Welsh pin "a pin, pen."

The transition from 'feather' to 'pin' (a slender or pointed instrument) appears to have been through 'pen,' a quill, to ' pen,' a style or stylus, hence any slender or pointed instrument [Century Dictionary]

As a part of a lock or latch, c. 1200; as a control for a mechanical device, late 14c. The modern slender wire pin, used as a fastener for clothing or in sewing, is attested by this name by late 14c., perhaps late 13c. Transferred sense of "leg" is recorded from 1520s and holds the older sense. The meaning "wooden stick or club set up to be knocked down in a game" (skittles, bowling, etc.) is by 1570s.

Pin-money "annual sum allotted to a woman for personal expenses on dress, etc." is attested from 1620s. Pins and needles "tingling sensation" is from 1810. The sound of a pin dropping as a type of something all but silent is from 1775.

c. 1200, pointe, "minute amount, single item in a whole; sharp end of a sword, etc.," a merger of two words, both ultimately from Latin pungere "to prick, pierce," from a nasalized form of PIE root *peuk- "to prick."

The Latin neuter past participle punctum was used as a noun, meaning "small hole made by pricking," subsequently extended to anything that looked like one, hence, "dot, particle," etc. This yielded Old French point "dot; smallest amount," which was borrowed in Middle English in the "smallest amount" sense by c. 1300. The meaning "small mark, dot" (mark made by the end of a pointed instrument) in English is from mid-14c.

Meanwhile the Latin fem. past participle of pungere was puncta, which was used in Medieval Latin to mean "sharp tip," and became Old French pointe "point of a weapon, vanguard of an army," which also passed into English (early 14c.). The senses have merged in English, but remain distinct in French.

 The sense of "peak or promontory from a land or coast" is from 1550s. The extended senses often are from the notion of "minute, single, or separate items in an extended whole." The sense of "brief period of time, instant" is from late 14c. Meaning "distinguishing feature" (especially a good one) is recorded from late 15c. Meaning "a unit of score in a game" is recorded from 1746.

The meaning "recognized unit of fluctuation of price per share on an exchange" is by 1814. As a typeface unit (in Britain and U.S., one twelfth of a pica), it went into use in U.S. 1883. As a measure of weight for precious stones (one one-hundredth of a carat) it is recorded from 1931. Meaning "diacritical mark indicating a vowel or other modification of sound" is from 1610s.

The point "the matter being discussed" is attested from late 14c.; meaning "sense, purpose, end, aim, advantage" (usually in the negative, as in what's the point?) is recorded by 1903. Point of honor (1610s) translates French point d'honneur. Point of no return (1941) is originally aviators' term for the point in a flight "before which any engine failure requires an immediate turn around and return to the point of departure, and beyond which such return is no longer practical" [Young America's Aviation Annual]. To make a point of "be resolved to do something and do it accordingly" is from 1778.