The pasuk itself (Devarim 33:4) uses the word מוֹרָשָׁה in the phrase "Torah that Moses commanded us, a heritage (morasha) of the congregation of Jacob," establishing it as a term for something inherited and possessed by a people.
Rashi (Devarim 33:4) reads morasha straightforwardly as an inheritance — something the congregation of Jacob has seized and will not relinquish — while the Ramban (Devarim 33:4) deepens the sense, explaining that the Torah shall be an inheritance for all the children of Jacob across every generation, never to be forgotten from the mouths of their descendants.
Sifrei Devarim 345:1 pushes further and offers a bold alternative reading: do not read morasha (inheritance) but me'orasah (betrothed), teaching that the Torah stands in the relation of a betrothed bride to Israel — a formulation that enriches the word's meaning from mere possession to intimate, covenantal bond.
The Kitzur Ba'al HaTurim (Shemot 6:8) notes that the word morasha appears twice in the Torah and connects the two occurrences, observing that the text writes morasha rather than yerushah — pointing to a distinction between one who bequeaths and one who inherits — and linking the inheritance of the Land to the merit of the Torah.