A compossessive construction is a strategy for a °predpossessive clause in which the °possessum nominal bears a °flag that is also used as a °comitative flag.
The definition is from Haspelmath (2025: 17), and the term is from Creissels (2020).
with-possessive strategy (a.k.a. companion strategy) (STR) = a strategy for the pres- entational possession construction in which the possessor is expressed in a subject phrase, and the possessum is expressed in a comitative phrase. Example: Amele ija sigin ca [I knife with] ‘I have a knife’ [lit. ‘I am with a knife’] is an instance of the with-possessive strategy. (Section 10.4.2)