English
marriage value
From marriage + value.
Today it means
noun The difference in value between a leasehold interest in land and the hypothetical value of its reversionary interest were the leasehold to be determined, which typically increases as the leasehold draws towards its end; frequently considered the market value chargeable to the tenant for a long extension of the leasehold, or for the purchase of the reversionary interest.
Language periods are conventional ranges, not dates for this word.
Etymograph / marriage value