"For example: if you visited, worked or lived in a country for two months, left for a few years, then returned for four months, that counts as spending six months there. In this case, you would need a certificate."
http://www.cic.gc.ca/english/information/security/police-cert/intro.asp
I think, this clearly means as IRCC counts six months as a cumulative time period spent in a country and/or a territory, then by lived they clearly mean the last time you were present in that country [for whatever reason, i.e., travel, visit, work etc]. And they count it up to the exit date, i.e. the time/date you left that country.