The Collaborative International Dictionary of English v.0.48:

Mensal \Men"sal\, a. [L. mensalis, fr. mensa table.]
   Belonging to the table; transacted at table; as, mensal
   conversation.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mensal \Men"sal\, a. [L. mensis month.]
   Occurring once in a month; monthly.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mensal
    adj 1: the dining table