in·val·id 2 
(ĭn-vălĭd)
(ĭn-vălĭd)adj.
1. Not legally or factually valid; null: an invalid license.
2. Falsely based or reasoned; faulty: an invalid argument.
[Latin invalidus, weak : in-, not; see IN-1 + validus, strong (from valēre, to be strong; see wal- in the Appendix of Indo-European roots).]
in′va·lidi·ty (-və-lĭdĭ-tē) n.
in·valid·ly adv.