Meaning
Usage

the lowest point of something

Example: My day was boring, but the nadir came when I accidentally spilled a bowl of spaghetti on my head.

"Nebulous" - (adjective) 

vaguely defined, cloudy

Example: The transition between governments meant that who was actually in charge was a nebulous matter.

habitually careless, neglectful

Example: Jessie’s grandfather called me a negligent fool after I left the door to his apartment unlocked even though there had been a recent string of robberies.

relating to or occurring during the night

Example: Jackie was a nocturnal person; she would study until dawn and sleep until the evening.

wandering from place to place

Example: In the first six months after college, Jose led a nomadic life, living in New York, California, and Idaho.

having a lack of concern, indifference

Example: Although deep down she was very angry, Marsha acted in a nonchalant manner when she found out that her best friend had used her clothing without asking.

widely and unfavorably known

Example: Jacob was notorious for always arriving late at parties.

harmful, unwholesome

Example: Environmentalists showed that the noxious weeds were destroying the insects’ natural habitats.

to assist the development of

Example: Although Serena had never watered the plant, which was about to die, Javier was able to nurture it back to life.

in the process of being born or coming into existence

Example: Unfortunately, my brilliant paper was only in its nascent form on the morning that it was due.

"Nefarious" - (adjective) 

heinously villainous

Example: Although Dr. Meanman’s nefarious plot to melt the polar icecaps was terrifying, it was so impractical that nobody really worried about it.

someone who is young or inexperienced

Example: As a neophyte in the literary world, Malik had trouble finding a publisher for his first novel.

unpleasant, offensive, especially to the sense of smell

Example: Nobody would enter the stalls until the horse’s noisome leavings were taken away.

trifling, insignificant

Example: Because he was moving the following week and needed to get rid of his furniture more than he needed money, Jordan sold everything for a nominal fee.

lacking a distinctive character

Example: I was surprised when I saw the movie star in person because she looked nondescript.

a beginner, someone without training or experience

Example: Because we were all novices at yoga, our instructor decided to begin with the basics.

a slight variation in meaning, tone, expression

Example: The nuances of the poem were not obvious to the casual reader, but the professor was able to point them out.