Sublinear or sub-linear means 'below linear' or 'less than linear', and may refer to:
- Sublinear function, a function from a vector space to a real number, that is positive-homogeneous and subadditive; all linear functions are also sublinear
- Sub-linear time, a time complexity of o(n), faster than linear
- Sublinear convergence / converging sublinearly, approaching a limit slower than linearly
