make up one`s mind - decide something I haven`t made up my mind about whether or not I will accept the new job. make up (something) - make something by putting things or parts together We made up the new machine by using parts from old machines. A car is made up of many different parts. make up (something/a story/an excuse) - invent a story, think and say something that is not true She made up the story about how she got lost in the mountains. make up (something/money/time) - do or supply something that is lacking, regain/repay something I had to make up the time that.