The real wordsTheory
The definition to write in the exam
Mutual fundAn investment company that issues its portfolio shares to investors. Money from shareholders is pooled and invested in a wide range of stocks, bonds or money market securities, managed by professional managers.
And the sentence about who bears what: each investor shares proportionately in the income and investment gains and losses, as well as the brokerage expenses and management fees.
SEBI's own wording adds the legal form: a common pool of funds invested in accordance with the objectives, held in a trust of which the investors alone are the joint beneficial owners.