Alost (Flem. Aalst), a town in the province of E. Flanders. Belgium, on the river Dender, which is navigable thus far, and 15 miles from Brussels on the railway to Ostend. The Church of St. Martin contains some fine pictures by Rubens, and the Town Hall is an interesting structure dating from the early 13th century. There are now large iron factories, and a good trade is done in lace, linen, wools, hops, and corn.