As far as I know, it's the word for any squash.
See the link below, it's in Indonesian, but it also mentions the Latin name (Cucurbitaceae) :
Labu merupakan buah yang dihasilkan oleh sejumlah anggota suku labu-labuan (Cucurbitaceae),...
The definition loosely translated : Labu is a fruit produced by all members of the Cucurbitaceae family.
The KBBI definition also mentions the same name (Cucurbitaceae):
For those who are wondering what squash means: 1.marrow 2. pumpkin 3. zucchini/courgette.