decedent: dead person
decadent: characterized by moral or cultural decline
descendant: going down
I hate it when that happens. 
A touch of Moon madness and let the slaughter begin!
Descendant is also a noun identifying someone/something who/that is descended from an ancestor.
Just to add to the confusion, there’s also
Descendent: an adjective describing someone/something who/that is descended from an ancestor.
Descendants are descendent.
25+ years ago on the University of Wisconsin-Madison’s engineering campus, a sculpture/water fountain was erected. It was supposed to be called “The Descendants’ Fountain”, but they screwed up and spelled it as “The Descendent’s Fountain,” cast in concrete. There was an expensive do-over and much embarrassment on the part of a large group of college-educated people who shoulda known better.
Inspired by a concurrent thread about banning abusively-exaggerated dog breed characteristics:
conformation: degree of physical resemblance to an official standard representing “ideal” characteristics, especially for a show animal. “The horse’s conformation flaws included a too-long neck and slightly turned-out knees.”
conformity: the practice of conforming to social conventions and norms so as not to seem “different” or “weird”. “In the 1950s the gray flannel business suit became a symbol of social conformity in general.”
confirmation: assurance or validation of a particular statement or condition. “The news broadcast provided confirmation of the rumors that had been circulating.”
like deformation and deformity
I’d’ve left it.
obtuse: unintelligent, indistinct/deficient in understanding or perception
obscure: indistinctly perceptible, dark.
(Classic example I’ve just read on a messageboard for the development I live in - one of the Board members just described some complainant’s message as “unclear, even obtuse”, so that thread may well run and run with offence taken, etc.!)
Thanks – makes that Shawshank Redemption scene a bit less…obscure.
specious: superficially plausible, but actually wrong.
speciose: applying to a taxonomic group - having many species. For example, the family Orchidaceae (orchids) is speciose, largely because each species of orchid has a small range.
spacious: having the characteristic of ample room for the intended use.
rout: a group of people; the retreat of an enemy force, to force into disorderly retreat
route: a road or way; to direct along a particular course
caliper(s): a device used to measure dimensions
caliber: the diameter of a round or cylindrical body
illicit: Unlawful, illegal, unpermitted
elicit: Evoke, prompt for, invite
yuca: alternate name for cassava
yucca: a genus of New World plants in the Asparagaceae family.
Note the fact that these show up in today’s NYT Spelling Bee is a coincidence. I had them in mind to submit it before seeing the puzzle.
virtual: in effect or essence, rather than in fact or reality; having efficacy due to some inherent natural qualities
virtuous: full of virtue; having excellent moral character
convenance: conventional propriety
convenience: the quality of being convenient: suitability, amenity
beneficent: given to acts that are kind, charitable, philanthropic, or beneficial
beneficial: helpful, good
benevolent: well wishing, having a disposition to do good
benefice: a permanent Church appointment, typically that of a rector or vicar, for which property and income are provided in respect of pastoral duties.
conveyance: an act or process of transportation or transfer; to convey something from one place or situation to another.
Also, a physical vehicle for conveying or transporting goods or people.
The source of the classic malapropism “A gentleman always gets up and gives his seat to a lady in a public convenience.” 
viscous: thick/sticky, neither quite liquid or solid
vicious: cruel, aggressive/violent, fierce