from The Century Dictionary.
- noun In law, a lease granted by a lessee for a shorter term than he himself holds, leaving thereby a reversion, of however short duration, to himself.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Law) A lease granted by a tenant or lessee; especially, a lease granted by one who is himself a lessee for years, for any fewer or less number of years than he himself holds; a sublease.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun law A
leasegranted by a tenantor lessee; a sublease.
from Wiktionary, Creative Commons Attribution/Share-Alike License
under- + lease
Easement rights, etc. would apply, but these might be limited to folks trying to enter/leave the city buildings not underlease.