This is from The Anchor Bible commentary series:
36. Cf. 24:34; the "coming" of The Man to the Father will certainly happen in this generation, when The Man is exalted in the glory of his passion-resurrection. The coming sufferings Jesus sees as judgment upon official Judaism for its refusal of him and his ministry.
... generation (Greek genea). This word may certainly mean "lifetime," and not simply "generation" in our sense of the term [...]. There is the same fluctuation of meaning in Biblical Hebrew dōr and Syriac dārā. — W. F. Albright and C. S. Mann, Matthew (The Anchor Bible).
I discovered in the 1980s, while surveying all the occurrences of
genea in the Greek OT, the fact, noted above by Albright and Mann, that in the New Testament as well as the Old Testament "there is the same fluctuation of meaning" in the usage of the Greek word
genea as in the usage of the Hebrew word
dōr — the former being the rendering of the latter throughout the Greek version of the OT.
The sense of
genea in Matthew as well as throughout the Greek OT is that of
dōr (
דור), which is defined in
A Concise Hebrew and Aramaic Lexicon of the Old Testament, edited by William L. Holladay, thus:
דור — circuit, lifetime, generation (from a man's birth to the birth of his first son; the totality of (adult) contemporaries; a time with its noteworthy events and people).