position prefix

A position prefix tells you where the root sits in space or in time: pre- before, post- after, sub- under, supra- above, infra- below, peri- around, inter- between, intra- within, retro- behind, trans- across. This course's prefix list is grouped by what a prefix does, and position is the largest group in it — and the most useful, because knowing one narrows the meaning of every word it appears in: pericardial is around the heart, subcutaneous is under the skin, intravenous is within a vein. Several have a time sense as well as a place sense — prenatal and postoperative are both about position in time — and the two senses rarely conflict, since before and after are positions on a line. The trap is a prefix that looks like one of these but is not: pre- is not the same as pro-, which means forward or in favor of.