There are multiple definitions:

1. orthogonal least square(English)

   • RBFNN
   • Statistics

2. ordinary least squares(English)

   • a regression method
   • ALS, BLS, BLUE, CBLS, CEIV, GLS, OLP, PLS, VIP, WLP, WLS
   • Statistics
   • https://doi.org/10.1002/sim.6872
   • https://doi.org…81.2009.05288.x

3. one leg stepping [movement](English)

   • EMG, TA
   • Musculoskeletal system
   • https://doi.org…n.1997.78.1.429