Copper compounds are used in fungicides and pesticides e.g. a traditional recipe is copper sulfate solution plus lime is used to kill greenfly.
wherewith
whereon
whereto
wherein
whomever
wholesale
wildcat
widespread
windward
wingspread
windpipe
wingspan
windstorm
windshield
windowpane
windlass
windflower
windsock
windswept
windmill
wintergreen
wiretap
wintertime
withstand
woodsman
woodcut
woodchuck
woodcarving
wolfhound
woodcutter
woodpecker
woodwork
woodwing
woolgathering
wisecrack
wishbone
wrongdoer
worldwide
workshop
workmanship
workmanlike
workday
workroom
worktable
yachtsman
caseous
casern
cashmerette
casque
cassation
castaneous
cassock
cassimere
cassideous
castellar
castellan
castellated
castophrenia
castory
castrametation
casualism
catabaptism
casuistry