noun, masculine/vɛ.ʁu.jaʒ ɡʁa.vi.ta.sjɔ.nɛl/plural: verrouillages gravitationnels
verrouillage gravitationnel is masculine in French.
tidal locking (the locking of the rotation of a satellite (moon or planet) to its orbit, such that one side always faces the body around which it is orbiting)