air-tight
    adj 1: having no weak points; "an airtight defense"; "an
           airtight argument" [syn: airtight, air-tight]
    2: not allowing air or gas to pass in or out [syn: airtight,
       air-tight, gas-tight]

Air-tight \Air"-tight`\, a.
   1. So tight as to be impermeable to air or other gases; as,
      an air-tight cylinder; -- said of containers.
      [1913 Webster]

   2. of such close construction as to have little leakage of
      air in or out; -- said of structures
      [WordNet 1.5]

   3. so thoroughly convincing as to be insusceptible to doubt;
      having no apparent counterarguments; -- of arguments or
      assertions an airtight alibi an airtight argument

   Syn: airtight, uncontradictable, undeniable.
        [PJC]

Air-tight \Air"-tight`\, n.
   A stove the draft of which can be almost entirely shut off.
   [Colloq. U. S.]
   [1913 Webster]