O - ar
obligar to force
observar to observe, to notice
to obtain, get, receive, acquire, come by; procure, secure; earn, achieve 
ocasionar to cause
ocultar to hide
ocupar to occupy
odiar to hate
olfatear to smell, to sniff out
olvidar to forget, to omit
olvidarse to forget oneself
operar to operate, to deal
opinar to give's one opinion
optar to opt, choose
orar to pray, to make a speech
ordenar to order, to put in order, to arrange
ordeñar to milk
organizar to organize
orientar to orientate, to direct, to guide
originar to originate, 
ostentar to show of, to flaunt
otorgar to concede, to grant
P - ar
pactar to agree to, agree on, to come to an agreement
pagar to pay, to pay for
palpar to touch, to feel, to caress
paralizar to paralyse
parar to stop
participar to take part, to notify, inform, participate
pasar to pass, to spend, 
pasear to walk, to take a walk, leisurely walk, stroll
patear to kick, stamp
patentar to patent
patinar to skate
patrocinar to sponsor
patrullar to patrol
pedalear to pedal
pegar to stick
peinar to comb
peinarse to comb one's hair
pelar to skin, to peel off, to cut one's hair
pelear to fight
pellizcar to pinch, nip
penalizar to penalize, punish, to give a penalty
penetrar to penetrate
pensar to think
perdonar to forgive
perdurar to last
perfeccionar to perfect, to improve, to enhance
perforar to perforate, to drill, to punch a hole in
perfumar to perfume, to scent
perjudicar to harm, to damage
permutar to exchange, to permute
perseverar to persevere
perturbar to disturb, to upset
pesar to weight
pescar to fish, to catch
pestañear to blink
peticionar to request, to plea
petrificar to petrify
picar to sting, to prick, puncture, to bite
picotear to peck, to chatter
pilotear to pilot, to steer
pinchar to prick, to puncture
pintar to paint
pisar to walk on, walk all over, step
pisotear to trample
planchar to iron
planear to plan
planificar to design, to organize
plantar to plant
plantear to set up, to pose
plastificar to make plastic jakets for hard books, laminate 
podar to prune
ponderar to speak in praise of,to praise highly
posar to put down, put gently, to land
posibilitar to make it possible
postular to apply for, to postulate
practicar to practise
predicar to preach
predominar to predominate
preguntar to ask, to question, to ask
preguntarse to ask fo sb.
prejuzgar to prejudge
premeditar to premeditate
premiar to reward
preocupar to worry
preparar to prepare, get ready
to get [oneself] ready , prepare [oneself]
presentar to present, to show, to display
preservar to preserv, to protect
presionar to press
prestar to lend, loan
presupuestar to budget for
presurizar to pressurize
privar to deprive, to forgive
probar to prove, to test, to try out
proclamar to proclaim
profundizar to go deeply
programar to programme
progresar to progress
prolongar to extend, to prolong, to make longer, extend
promocionar to promoting
pronosticar to predict, foretell, forecast
pronunciar to pronunce
proporcionar to provide, to supply, to give
prorratear to prorate, apportion
prorrogar to extend, to defer, to postpone
prosperar to prosper, to flourish, thrive
protagonizar to be the protagonist, the main character
protestar to protest
provocar to provoke
proyectar to hurl, throw, to cast, shed, to sceen, show, to plan
publicar to publish, to publicize, to make public, divulge
pujar to bid up, make an effort
pulverizar to pulverize, to spray
purificar to purify