an act of assuming control of something, especially the buying out of one company by another.
"they sought a controlling interest rather than a takeover"
synonyms: gaining of control, change of ownership, purchase, acquisition, buying;
The verb form is two words: "take over". And the "especially" does not apply. The phrase can refer to any situation, such as a computer taking over some function formerly performed by people, or a population of animals taking over an area formerly occupied by other animals.