pith

Etymology 1

From Middle English pith, pithe, from Old English piþa, from Proto-Germanic *piþô (compare West Frisian piid (“pulp, kernel”), Dutch peen (“carrot”), Low German Peddik (“pulp, core”)), from earlier *piþō (oblique *pittan). Doublet of pit. The verb meaning "to kill by cutting or piercing the spinal cord" is attested 1805.

noun

1. (botany) The soft, spongy substance in the center of the stems of many plants and trees.
2. The spongy interior substance of a feather or horn.
3. (anatomy) The spinal cord; the marrow.
4. (botany) The albedo of a citrus fruit.
5. (figurative) The essential or vital part; force; energy; importance.
   The pith of my idea is that people should choose their own work hours.
6. (figurative) Power, strength, might.

verb

1. (transitive) To extract the pith from (a plant stem or tree).
2. (transitive) To kill (especially cattle or laboratory animals) by cutting or piercing the spinal cord.

Etymology 2

From pi (“number 3.14159...”) + -th.

adj

1. The ordinal form of the number pi.
   The pith root of pi is approximately 1.439...
   e, which is the reciprocal of the square root of e to the pith power. 1998/06/21, “For what x is x^x real?”, in alt.algebra.help (Usenet), message-ID <6mhv6n$13l$1@nnrp1.dejanews.com>
   That's nothing. I have an IMEI changer that will do all of the above and beat you off at the same time, while whistling the adaggio from Spartacus in Armenian and calculating pi to the pith power in swahili. 2000-08-09, alice, “Re: Eyecandy: Meet Compton the new Lightweight Composite Manager”, in aus.comms.mobile (Usenet), message-ID <B5B6F806.53B5%alice@alice-didit.com>
   already, we know what is minus one from Euler: it is the I*pith power of e, such that ln(-1) = i*pi 4 Mar 2017, “The non existence of p'th root of any prime number, for (p>2) prime”, in sci.math (Usenet), message-ID <cabe6746-8a13-44f0-9e95-30eec727654a@googlegroups.com>

noun

1. One divided by pi.
   not only that, but your "radian" axis can be labelled as *being* in units of pis, as opposed to the redundancy of 0pi, pi/2, pi etc.; conversely, your circumferential measure can be rational (or units) and your radius can be transcendental (or piths .-) 1997-04-26, Brian Hutchings, “Re: Trigonometric Functions”, in sci.math (Usenet), message-ID <1997Apr26.204554.24471@lafn.org>
   thought it was the two-sixths power of pi, and teh secondpower of six piths 2016-04-01, abu.ku...@gmail.com, “Re: pi^2/6 and 6/pi^2”, in sci.math (Usenet), message-ID <d1d13d13-c4c0-43c3-b4cb-7911dcb24cc7@googlegroups.com>
   of course, although a pith is less than a third, hence pi is more than three, say, thirty-one tenths, but 22/7 is still less than pi, and that's a rather small gore 2017-01-13, thugst...@gmail.com, “pith is at most a third”, in sci.physics (Usenet), message-ID <89a35ff8-1df1-4ab5-baf5-fdc605207710@googlegroups.com>