Words and Phrases - "defeasible"

Heald JA summarized findings of the trial judge (p. 5279), which he later adopted (at p. 5281) as being "accurately stated":

1. that an interest is vested if (a) the person entitled to it is ascertainable and, (b) that person can take possession forthwith and can only be prevented from doing so by the existence of some prior interest. A vested interest is distinct from a contingent interest, which gives no right of enjoyment unless or until a future event occurs (a condition precedent); and
2. that a vested interest is defeasible if it is subject to a condition subsequent or determinable limitation which condition or limitation must be contained in the grant.