![o-Toluidine][1] ![o-Toluic Acid][2] [1]: https://i.sstatic.net/IrZpv.png [2]: https://i.sstatic.net/nlLYy.jpg When comparing $\ce{o,m,p-Toluidine}$, basicities, *Ortho Effect* is stated as a reason why o-toluidine is weaker But, When comparing $\ce{o,m,p-Toluic Acid}$ basicities, *Ortho Effect* is stated as a reason why o-toluic acid is stronger acid And, I was given the definition that *Ortho Effect* is an effect in which an ortho- group causes steric hindrance, forcing the $\ce{-COOH}$ or $\ce{-NH2}$ or some other bulky group to move out of the plane, inhibiting resonance. Then, If Ortho Effect inhibits resonance, why is $\ce{o-Toluic Acid}$ the strongest and $\ce{o-Toluidine}$ the weakest? If not, What exactly is Ortho Effect?