The complex patronage relationships changed with the social pressures during the late Republic, when terms such as patronus, cliens and patrocinium are used in a more restricted sense than amicitia, "friendship" including political friendships and alliances, or hospitium, reciprocal "guest-host" bonds between families.[17] It can be difficult to distinguish patrocinium or clientela, amicitia, and hospitium, since their benefits and obligations overlap.[18] Traditional clientela began to lose its importance as a social institution during the 2nd century BC;[19] Fergus Millar doubts that it was the dominant force in Roman elections that it has often been seen as.[20]