| Term | Definition |
| antacid | a substance that works against stomach acid |
| antibacterial | designed to fight against or kill bacteria |
| antidote | a remedy or cure;something that works against a poison |
| antihistamine | a medicine that works against colds and allergies |
| antonym | a word that means the opposite of another word |
| retroactive | goes back to a prior time |
| retrofit | to go back and install something that was not available at the time of original manufacturing |
| retrospective | characterized by looking back at the past and reflecting;related to the past |
| probable | likely;likely to move in a positive direction |
| proceed | to move foward;to go;to follow through with an idea or plan |
| projectile | a foward-moving object that was trown or self-powered |
| prolong | to draw out;to make something moving foward last longer |
| promotion | a movement foward in a company;a movement up into a better position in a job |
| propel | to cause to move foward |
| prospect | the act of looking foward in anticipation of something to come |
| protest | to foward a complaint,objection,or diplay of unwillingness |