From DT Online
Jigsaws are small hand held power tools with reciprocating blades. They are much used for cutting flat shapes out of sheets of ply and other manufactured boards but metal cutting, and ceramic cutting, blades are also available. Many have a tilting base to enable cutting of bevels.
Safety point! Students may only use reciprocating portable saws where they have been assessed and the assessment shows that they are competent, and are under appropriate supervision of specifically trained staff.
Note: In 1880, with the introduction of the treadle saw, what had previously been known as dissections came to be known as jigsaw puzzles, although they were actually cut by a fretsaw, not a true jigsaw.