AUXILIARY, that which gives aid or support (from Lat. auxilium, help) ; the term is used in grammar of a verb which completes the tense, mood or voice of another verb; in engineer ing, e.g., of the low steam power used to supplement the sail-power in sailing ships; in military use of foreign or allied troops, more properly of any troops not permanently maintained under arms. In the British army the term "Auxiliary Forces" was employed formerly to include the Militia, the Imperial Yeomanry and the Volunteers. So long as infantry was held to be the decisive arm, the term "auxiliary arms" was often used to mean the other arms, especially artillery, which assisted it in this role and gave fire support to its assault.