molecular geometry
A molecule is not a flat doodle on paper; it is a real arrangement of atoms in three dimensions, with definite angles and distances. Molecular geometry is the name for that actual shape — whether a molecule is straight, bent, flat-triangular, pyramidal, or something more elaborate. Shape is not a cosmetic detail: it controls polarity, reactivity, how molecules pack and fit together, and in biology whether a molecule works at all.
Geometry is set by how many bonding pairs and lone pairs surround the central atom (the electron-region count from VSEPR). Some standard names: two regions give linear (CO2, BeCl2); three give trigonal planar (BF3) or, with one lone pair, bent (SO2); four give tetrahedral (CH4), trigonal pyramidal (NH3, one lone pair) or bent (H2O, two lone pairs); five give trigonal bipyramidal (PF5) and, as lone pairs replace bonds, see-saw (SF4), T-shaped (ClF3) and linear (XeF2, I3-); six give octahedral (SF6), square pyramidal (BrF5) and square planar (XeF4). The shape always describes only the positions of the atoms, with the lone pairs invisible in the name even though they helped set the angles.
Molecular geometry is the payoff of drawing Lewis structures and applying VSEPR, and it is everywhere in inorganic chemistry. The bent shape of water gives it a net dipole and hence its remarkable solvent power; the tetrahedral shape of phosphate and sulfate underlies their roles in biology and minerals; the square-planar geometry of certain d8 complexes such as cisplatin is exactly what lets the drug grip DNA. Get the geometry right and a great deal of chemistry follows.
SF4 has five electron regions around sulfur: four S-F bonds and one lone pair. The lone pair takes an equatorial spot in the trigonal bipyramid, so the atoms trace out a distinctive see-saw shape rather than a symmetric one.
Replacing one bond of a trigonal bipyramid with a lone pair gives the see-saw shape of SF4.
Geometry names refer to atom positions only, so the electron arrangement and the shape can have different names: water has a tetrahedral electron arrangement but is described as bent because we ignore the two lone pairs.