What is a Disciple?
The disciples (Pali: sāvaka) of a given Buddha (any Buddha, that is, not just of Buddha Gotama) are those who accept the Buddha as their teacher and attempt to follow his path. By taking refuge in the Triple Gem, in the Buddha, the Dharma, and the Sangha, we too are disciples of the Buddha, we too are his sāvaka.
The concept of sāvaka cuts across the traditional four-fold division of the great assembly of Buddhist followers in to lay women practitioners, ordained women practitioners (the Bhikkhunis), lay men practitioners, and ordained men practitioners (the Bhikkhus).
One need not be a Bhikkhuni or a Bhikkhu to be a disciple of the Buddha.
 Great Disciples, p. XVI.
 I say “greater assembly” since in the Theravādan tradition the term ‘Sangha’ refers only to the community of Bhikkhus and Bhikkhunis. But as we can see there is also a greater, inclusive sense of the Buddha’s followers which counts all practitioners, both ordained and non-ordained.