- tactSensitive mental touch; special skill or faculty; keen perception or discernment; ready power of appreciating and doing what is required by circumstances; the ability to say the right thing and avoid statements that will give offence or pain even if true.
- tacnodeA point of a curve where two or more osculating circles to the curve at that point are tangent, so that two branches of the curve have ordinary tangency at the double point.
- tactusThe sense of touch.