The trait of being uncommunicative; not volunteering anything more than necessary.

synonyms: reserve, reticence.

Roget 585: silence, muteness, obmutescence^†; taciturnity, pauciloquy^†, costiveness^†, curtness; reserve, reticence etc. (concealment) 528.    man of few words.   

Dutch: zwijgzaamheid, gereserveerdheid, geslotenheid, reserve, terughoudendheid
Polish: milczkowatość, mrukliwość, burkliwość, mrukowatość, milkliwość, małomówność