The most common single masted sailing vessel with a mainsail and one jib is the sloop.
A cutter has one mast with one mainsail but two jibs.
A catboat has one mast and a huge mainsail but (usually) no jib. The mast is located very much forward on the vessel.
There are other sailboats that have just one mast and a mainsail such as the Sunfish or a Dhow, both of which have a lateen rig (one mast, one mainsail.)
there is no such thing as a small two-masted vessel with a mainsail and jib
special
Sloop.
A sloop
schooner
A ketch or a yawl.
catalina capri 14
a dinghy would be a small (6 to 16 foot) sailboat, these can have almost any sail rig. the type of rig you described is called a sloop. a sloop is a sailboat with a triangular mainsail and a jib (this sail configuration is called a marconi rig, or bermudian rig), and are very common. so a small, one masted vessel with a mainsail and jib would just be called a sloop, or dinghy.
Yawls, ketches and two-masted schooners all match this definition. The jib or headsail is not used to define the boat, as almost all fore-and-aft rigged boats have a headsail of some kind.
Sloop rig
A ketch or a yawl.
A Jib is a secondary sail which is generaly smaller than the mainsail, and is usually possitioned at the frount of a boat (a foresail). It is generally triangular and is used to counteract the turning force of the mainsail around the pivot point of the vessel in some classes of boat.