Perhaps you should try some spelling variations:
"synchronised swimming" » "synchronized swimming", "synchronised stemming"
"synchronism swimming" » "synchronism stemming"
"synchronising swimming" » "synchronising stemming", "synchronisations swimming"
"synchronizing swimming" » "synchronizing stemming"
"synchronize swimming" » "synchronize stemming"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("synchronised swimming") or ((("synchronism swimming") or ((("synchronising swimming") OR ("synchronizing swimming"))))))) or ("synchronize swimming"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("synchronised swimming") OR ((("synchronism swimming") OR ((("synchronising swimming") OR ("synchronizing swimming"))))))) OR ("synchronize swimming")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"synchronised swimming\") or (((\"synchronism swimming\") or (((\"synchronising swimming\") OR (\"synchronizing swimming\"))))))) or (\"synchronize swimming\"))".
• Removing quotes may allow a broader search: (((( synchronised swimming ) or ((( synchronism swimming ) or ((( synchronising swimming ) OR ( synchronizing swimming ))))))) or ( synchronize swimming )).
• Adding a wildcard symbol may retrieve word variants: (((("synchronised swimming") or ((("synchronism swimming") or ((("synchronising swimming") OR ("synchronizing swimming"))))))) or ("synchronize swimming"))*.