Less
A quantity 
is said to be less than 
if is smaller than , written 
. If is less than or Equalto , the relationship is written 
. If is Much Less than , this is written 
. Statementsinvolving Greater than and less than symbols are called Inequalities.
- Nyquist Sampling
- Néron-Severi Group
- Nöther
- Obelus
- Object
- Oblateness
- Oblate Spheroid
- Oblate Spheroidal Coordinates
- Oblate Spheroidal Wave Function
- Oblate Spheroid Geodesic
- Oblique Angle
- Oblong Number
- Obstruction
- Obtuse Angle
- Obtuse Triangle
- Ochoa Curve
- Octacontagon
- Octadecagon
- Octagon
- Octagonal Number
- Octagram
- Octahedral Graph
- Octahedral Group
- Octahedral Number
- Octahedron