Which meant that one must own or rent land, freehold (not leasehold
to the value of forty shillings or more (at the time of the Catholic Relief Bill 1793 this was a value of around £2). .
All freehold involves owning the land, never renting the land. If you have an agreement to hand the land back to somebody else one day (even in 999 years), it is not freehold.
There used to be various other kinds of land tenancy other than freehold and leasehold which haven't existed (at least in England) since 1925. http://en.wikipedia.org/wiki/Copyhold I don't know to what extent these were relevant to Ireland.