<word meaning and root formation>

Nanocephalous: having an abnormally small head [Gk. nânos (“small”) + -cephal (“head”) + -ous]

Nasute: having an acute or sensitive sense of smell; having a long snout [from L. nāsus (“nose”) +‎ -ūtus]

Naupathia: sea-sickness [Gk. naus (“ship”) + -pathos (“suffering”)]

Necromorphous: feigning death to deter an aggressor [from Gk. necro (“death”) + –morphe (“form”)]

Nefandous: unspeakable; unutterable [from L. ne- (“not”) + –fandus,  ➨ –fārī (“to speak”)]

Neoteny: an indefinite prolongation of the period of immaturity, with the retention of infantile or juvenile qualities, into adulthood [from Gk. néos “young” + -o--O- + -teínein (“to stretch”; “extend”) + -y]

Nepheligenous: producing clouds of smoke [from Gk. nephélē, (“cloud”) +‎ -genous (“producing). Coined by OW Holmes]

Neopotation: prodigality; extravagance; squandering one’s money on riotous living (OU)

Nidifugous: leaving the nest while still young [L. nīdus (“nest”) + –fugiō (“I flee”; “escape”) + -ous]

Nikhedonia: the pleasure and satisfaction derived from the anticipation of success [nik(?) poss. from Nike, Greek god of victory + Gk. –hedonikos (“pleasure”)]

Nimiety: excess; extravagance; surfeit [from L. nimius (“excessive”)]

Nocent: harmful [from L. nocens (“to harm”)]

Noctivagant: wandering by night [from L. nocti- (“night”) + –vagari (“to wander”)] 🌃

Noisome: noxious; smelly; nasty [from MidEng. noy (“annoyance”) + -some, (“characterised by a specified thing,”)] 

Nonfeasance: failure to perform some action which ought to have been performed [L. non- + Eng. -feasance (“doing”; “execution”)]

Nostrificate: to accept as one’s own; to grant recognition to a degree (or other formal qualification) from a foreign university (or other registered educational institution) [from L. noster (“our”) + -cate]

Noyade: mass execution by drowning (esp in revolutionary France in Nantes, 1793-94) [from L. necare (“kill without using a weapon”) (nonce word)]

Nugacity: triviality; futility; drollery (cf. nugatory: of no value; trifling; pointless) [from L. nugacitas (“trifling”)]

Nullibiety: the state of being nowhere [from L. nūllus (“none”; “no”; “not any”) +‎ –ibī (“there”) + -ety] (cf. Nullibist: one who denies that the soul exists in physical space)

Numen: pertaining to numina; awe-inspiring; supernatural) [L. nuō + –men (“a nodding with the head”; “command”; “will”)]

Nummamorous: money-loving (cf. Nummary: pertaining to coin) (OU) 💴 🪙

Numinous: divine; spiritual” [from L. nūmen]

Nuncheon: a noon drink [from MidEng. nonshench, noneschench, nonechenche (“slight refreshment, usually taken in the afternoon”) from L. nōnus] 🍷

Nutation: the act of nodding the head, esp habitually or constantly; a periodic variation in the inclination of the axis of a rotating object [from L. nūtātiō (“nodding”), from nūtō (“I nod”)]

Nycterent: someone who hunts by night [from Gk. nyct (“night”) + -ent] (cf. Nyctitropic: turning in a certain direction at night) (cf. Nyctalopia: night-blindness)

Nympholepsy: a passionate longing for something unattainable [from Gk mythology: nymphóleptos (“possessed by nymphs”)]

Key: OU = origin unknown

<word meaning and root formation>

Obsidional or Obsidionary: pertaining to a siege [from L.  obsidiō (“siege”; “blockade”)]

Obsolagnium: waning sexual desire due to age [from L. ob- (“against”) + lagnium (“desire”)]

Obtund: to blunt, dull or deaden [from L. obtundere (“to dull”, “deaden”, “deafen”)]

Oculogyric: eye-rolling; rotation of the eyes [from L. oculo- (“eye”) + –gyric, from Gk. -gurus (“circle”)]

Oligophagos: eating only a few particular kinds of food [from Gk. olig (“few”) + –phagos (“eating”)]

Ollapod: pharmacist; (Orig. a country apothecary [name of a character in George Colman the Younger‘s comedy The Poor Gentleman (1801)]

Ombrophilous: capable of withstanding heavy and continuous rain [from Gk. ómbros (“rain”) + –philous (“love”)]

Omniety: the state or condition of being all [from L. omnis (“all”) + -iety]

Oneirataxia: inability to distinguish between fantasy and reality [Gk. oneiros (“dream” + –taxis (“arrangement”)]

Onomasticon: an ordered list of names (Orig. a gazetteer of historical and contemporary 4th-century place names in Palestine and Transjordan compiled by Eusebius) [Gk. onomastikós, (“belonging to names”), from onomázō, (“I name”)]

Onychophagia: nail-biting [from Gk. onych (“claw”) + -phagos].

Ophelimity: the ability to please another; economic satisfaction [from Gk. ōphélimos, (“helpful”)]

Opisthenar: back of the hand [from Gk. opistho- (“behind”; “back”) +‎ –thenar (“palm of the hand”)] 🤚

Opsablepria: inability to look someone in the eye (OU) 👁️

Orarian: dweller by the seaside; relating to the seaside [from L. ōrārius (“coasting”; “along the coast”) + -an]

Orthostatic: relating to standing upright; straight posture [Gk. orth (“right angle”; “perpendicular”) + –statikós (“to make stand”)] (cf. Orthobiosis: a hygienic and moral lifestyle)

Osophagist: a fastidious eater [Gk. (?) + –phagos]

Otiose: serving no useful purpose; leisurely (cf. Otiant: idle or resting [from L. otium (“leisure”)]

Ozostomia: evil-smelling breath [from Gk ozóstom(os) (“having bad breath”)]

Key: OU = origin unknown