Merriam-Webster's Collegiate Dictionary:
rc
rcaf
rcmp
rcn
rd
rda
rdf
re
re infecta
re-
re-collect
re-cover
re-creatable
re-create
re-creation
re-creative
re-creator
re-form
re-lease
re-present
re-presentation
re-press
re-sign
re-sort
re-tread
re-up
rea
reabsorb
reach
reach-me-down
reachable
reacher
react
reactance
reactant
reaction
reactionary
reactionaryism
reactive
reactively
reactiveness
reactivity
reactor
read
read between the lines
read out
read the riot act
read-only memory
readability
readable
readableness
readably
reade
reader
readerly
readership
readily
readiness
reading
reading desk
reading frame
readout
ready
ready box
ready room
ready-made
ready-to-wear
ready-witted
readymade
reafforest
reafforestation
reagan
reaganesque
reagent
reaggregate
reaggregation
reagin
reaginic
real
real estate
real focus
real image
real number
real part
real presence
real time
real-life
real-time
real-valued
real-world
realgar
realia
realign
realignment
realisation
realise
realism
