Perhaps you should try some spelling variations:
"synchronised swimming" » "synchronize swimming", "synchronising swimming"
"synchronism stemming" » "synchronize stemming", "synchronising stemming", "synchronism steering", "synchronism flemming", "synchronism stealing"
"synchronism stepping" » "synchronize stepping", "synchronising stepping", "synchronism stopping", "synchronism shopping", "synchronism shipping"
"synchronized stemming" » "synchronized steering", "synchronized flemming", "synchronized stealing"
"synchronized streaming" » "synchronized treating"

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 stemming") OR ("synchronism stepping"))) or ((("synchronized stemming") or ("synchronized streaming"))))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("synchronised swimming") OR ((((("synchronism stemming") OR ("synchronism stepping"))) OR ((("synchronized stemming") OR ("synchronized streaming")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"synchronised swimming\") or (((((\"synchronism stemming\") OR (\"synchronism stepping\"))) or (((\"synchronized stemming\") or (\"synchronized streaming\"))))))".
• Removing quotes may allow a broader search: (( synchronised swimming ) or ((((( synchronism stemming ) OR ( synchronism stepping ))) or ((( synchronized stemming ) or ( synchronized streaming )))))).
• Adding a wildcard symbol may retrieve word variants: (("synchronised swimming") or ((((("synchronism stemming") OR ("synchronism stepping"))) or ((("synchronized stemming") or ("synchronized streaming"))))))*.