to puzzle, perplex, baffle, bewilder (somebody); to afflict by being complicated, contradictory, or otherwise difficult to understand
To mix up, muddle up (one thing with another); to mistake (one thing for another).
To mix thoroughly; to confound; to disorder.
To be confused.
To design and construct the contours of a vehicle etc. so as to offer the least resistance to its flow through a fluid.
To simplify or organize a process in order to increase its efficiency.
To modernise.
On a weather chart, a line that is tangent to the flow of the wind.
A line that is tangent to the velocity of flow of a fluid; equivalent to the path of a specific particle in that flow.