The Collaborative International Dictionary of English v.0.48:
Boiler \Boil"er\, n.
1. One who boils.
2. A vessel in which any thing is boiled.
Note: The word boiler is a generic term covering a great
variety of kettles, saucepans, clothes boilers,
evaporators, coppers, retorts, etc.
3. (Mech.) A strong metallic vessel, usually of wrought iron
plates riveted together, or a composite structure
variously formed, in which steam is generated for driving
engines, or for heating, cooking, or other purposes.
Note: The earliest steam boilers were usually spheres or
sections of spheres, heated wholly from the outside.
Watt used the wagon boiler (shaped like the top of a
covered wagon) which is still used with low pressures.
Most of the boilers in present use may be classified as
plain cylinder boilers, flue boilers, sectional and
Barrel of a boiler, the cylindrical part containing the
Boiler plate, Boiler iron, plate or rolled iron of about
a quarter to a half inch in thickness, used for making
boilers and tanks, for covering ships, etc.
Cylinder boiler, one which consists of a single iron
Flue boilers are usually single shells containing a small
number of large flues, through which the heat either
passes from the fire or returns to the chimney, and
sometimes containing a fire box inclosed by water.
Locomotive boiler, a boiler which contains an inclosed fire
box and a large number of small flues leading to the
Multiflue boiler. Same as Tubular boiler, below.
Sectional boiler, a boiler composed of a number of
sections, which are usually of small capacity and similar
to, and connected with, each other. By multiplication of
the sections a boiler of any desired capacity can be built
Tubular boiler, a boiler containing tubes which form flues,
and are surrounded by the water contained in the boiler.
See Illust. of Steam boiler, under Steam.
Tubulous boiler. See under Tubulous. See Tube, n., 6,
and 1st Flue.