Actually it's a bit different, though you've got the right idea.
Crowding out assumes a closed economy (as such it really no longer applies today, but you still need to learn it).
It states that since there is a fixed amount of savings available to fund investment, an increase in government spending to boost economic growth would need to use up some of these savings. As the federal government is the safest organisation to invest with, all other firms must offer a premium on the interest rates offered by the government in order to get the funds they need. This increase in interest rates reduces private business investment and it is said that the government has "crowded out" the private sector.