Definitions:
chief in size or importance

a principal pipe carrying water or gas to buildings, or taking sewage from them

the open ocean.

(in the game of hazard) a number (5, 6, 7, 8, or 9) called by a player before dice are thrown.

a match between gamecocks.

a river of south-western germany which rises in northern bavaria and flows 500 km (310 miles) westwards, through frankfurt, to meet the river rhine at mainz.