Forth, river, c.60 mi (100 km) long, formed by streams that join near Aberfoyle in Stirling, S central Scotland. It meanders generally eastward past the town of Stirling to the Firth of Forth at Alloa. Its chief tributaries are the Teith and Allan rivers. The Firth of Forth extends c.55 mi (90 km) E from Alloa to the North Sea, reaching widths up to 19 mi (31 km) across. Rosyth is an important naval base, and Leith is the port of Edinburgh. The port of Grangemouth is at the eastern end of the Forth and Clyde Canal (35 mi/56 km long; completed 1890), which links the Firth of Forth with the River Clyde. Rivers flowing into the firth include the Leven, Esk, Avon, and Carron. The Isle of May and Bass Rock, with lighthouses and ruins, are at the entrance to the firth; Inchkeith and Inchcolm islands are within the firth. At Queensferry three bridges cross the firth—the Forth Bridge (completed 1936); the Forth Road Bridge, one of the longest suspension bridges in Europe (3,300 ft/1,006 m long; completed 1964); and the Forth Railway Bridge (5,350 ft/1,631 m; completed 1890), the world's first cantilever bridge.

FORTH A programming language formerly much in vogue among users of microcomputers. FORTH operands are held on a stack, and programs take the form of strings in reverse Polish notation. A vital feature of FORTH is that a symbol (a WORD) can be associated with any program string, and such a user-defined word can then be used in expressions on equal terms with the system words (operators). This makes FORTH a flexible extensible language in which it is possible to define a customized language for, say, the control of a scientific instrument. The FORTH system is very compact; the interpreter and the dictionary containing the system-defined words can be fitted into 8K bytes. FORTH is now little used, but the same principles are found in PostScript.

forth forwards (now only in back and forth); onwards (surviving in gen. use in and so forth); forward into view; away. OE. forð = OS. forth (Du. voort), MHG. vort (G. fort) :- Gmc. *furþa (cf. Goth. faurþis further) :- IE. *pṛto-, f. base repr. in FORE-. forthcoming about or ready to appear XVI; ready to make advances XIX. forthright OE. forðriht adj., -rihte adv. forthwith †at the same time; immediately XIV; partly short for earlier forthwithal (XI), partly repl. ME. forth mid along with, at the same time as, used absol.

forth / fôr[unvoicedth]/ • adv. chiefly archaic out from a starting point and forward or into view: the plants will bush out, putting forth fresh shoots. ∎  onward in time: from that day forth he gave me endless friendship. PHRASES: and so forth and so on: particular services like education, housing, and so forth.

forth •forth, fourth, henceforth, north, thenceforth