FIR - A conifer of the genus Abies.
FIX - A repair or corrective action.
PER - For each.
PIE - A type of pastry that consists of an outer crust and a filling.
RIP - A tear (in paper, etc.).
REP - Short form of reputation.
REF - Referee.
FIRE - A (usually self-sustaining) chemical reaction involving the bonding of oxygen with carbon or other fuel, with the production of heat and the presence of flame or smouldering.
PIER - A raised platform built from the shore out over water, supported on piles; used to secure, or provide access to shipping; a jetty.
RIPE - Ready for reaping or gathering; having attained perfection; mature; -- said of fruits, seeds, etc.; as, ripe grain.
RIFE - Widespread, common (especially of unpleasant or harmful things).
FIXER - Agent noun of fix; one who, or that which, fixes.
PREFIX - That which is prefixed; especially one or more letters or syllables added to the beginning of a word to modify its meaning; as, pre- in prefix, con- in conjure.