What is Quasi Estate Tail?

Legal Definition
When a tenant for life grants his estate to a man and hisheirs, as these words, though apt and proper to create an estate tail, cannot do so,because the grantor, being only tenant for life, cannot grant in perpetuum, thereforethey are said to create an estate tail quasi, or improper, llrown.
Legal Definition
An estate tail of less than a fee, e. g., an estate tail pur autre vie.
-- Ballentine's Law Dictionary