Quenya 

-twa

their

-twa 2) an pronominal possessive ending mentioned in one chart of pronouns, apparently "their" referring to two persons (VT49:16); this may be an ending used in colloquial Quenya rather than formal language (it is listed together with the endings -ya "his, her" and -rya "their", that are explicitly said to belong to colloquial Quenya) (VT49:16-17)