In the Companies Acts"undertaking" means—
a body corporate or partnership, or
an unincorporated association carrying on a trade or business, with or without a view to profit.
In the Companies Acts references to shares—
in relation to an undertaking with capital but no share capital, are to rights to share in the capital of the undertaking; and
in relation to an undertaking without capital, are to interests—
conferring any right to share in the profits or liability to contribute to the losses of the undertaking, or
giving rise to an obligation to contribute to the debts or expenses of the undertaking in the event of a winding up.
References in the Companies Acts to "fellow subsidiary undertakings" are to undertakings which are subsidiary undertakings of the same parent undertaking but are not parent undertakings or subsidiary undertakings of each other.
In the Companies Acts "group undertaking", in relation to an undertaking, means an undertaking which is—
a parent undertaking or subsidiary undertaking of that undertaking, or
a subsidiary undertaking of any parent undertaking of that undertaking.