[{"Bold_text": "noun", "List Items": ["Civil Engineering.an airtight chamber permitting passage to or from a space, as in a caisson, in which the air is kept under pressure.", "the impedance in the functioning of a pump or a system of piping caused by the presence of an air bubble; vapor lock."]}, {"Bold_text": "verb (used with object)", "List Items": ["to place in or confine to an air lock:to air-lock divers before they descend."]}]