George Junior says his favorite weird word is:
The eighth power of a number.
This word is long obsolete, so much so that the Oxford English Dictionary only has one citation for it, from a famous work by the Welsh-born mathematician Robert Recorde, The Whetstone of Wit, published in 1557. It turns up from time to time as one of those weird words which is best known for being held up as an example of a weird word.
Go here to find one.