obsolete,no longer used
obstreperous,noisy/loud 
obtain,to be established/accepted or customary
obtrusive,projecting/prominent/undesirably noticeable 
obviate,to make unnecessary/get rid of 
occluded,blocked up
occult,hidden/concealed/beyond comprehension 
odious,repulsive/hateful
odium,contempt/dislike/aversion 
odor,smell/favor/reputation
officious,too eager or ready to help/offer advice
onerous,needing effort/burdensome
opprobrious,showing scorn or reproach
opulence,a wealth
ossify,to turn to bone/to settle rigidly into an idea
ostensible,seeming/appearing as such/professed 
ostentation,display to obtain admiration or envy
ostentatious,fond of showing ostentation
ostracism,shut out from society/refuse to meet/talk
ostrich,fast-running bird unable to fly
outset,start
overhaul,examine thoroughly to learn about the condition
overweening,presumptuously arrogant/overbearing/immoderate/being a jerk 
overwhelm,weigh down/submerge
pacifist,one opposed to force/an antimilitarist
paean,song of praise or triumph
palate,roof of the mouth/sense of taste
palatial,magnificent
palliate,lessen the severity of
palliate,to make something appear less serious/to alleviate
palpability,can be felt/touched/understood
palpitate,tremble/beat rapidly and irregularly
panegyric,formal praise/eulogy 
paradigm,a model/example or pattern 
parenthesis,sentense within another one/smth separated
pariah,an outcast/a rejected and despised person 
parsimonious,too economical/miserly
partisan,one-sided/committed to a party/biased or prejudiced
patron,regular customer/person who gives support
paucity,scarcity/a lacking of 
peccadillo,small sin/small weakness in one's character
pedantic,bookish/showing off learning 
pedestrian,commonplace/trite/unremarkable 
pellucid,transparent/easy to understand 
penchant,strong inclination/a liking
penitent,feeling or showing regret 
penury,extreme poverty 
peregrination,traveling about/wandering 
peremptory,urgent/imperative/unchallengeable/ending debate 
perennial,lasting for a long time (a year)