śaikṣa [sekha] a learner. The term means one who pursues training (śikṣā). The threefold training consists of that in morality (adhiśīla-śikṣā), in higher mentality (adhicitta-śikṣā) and in higher wisdom (adhiprajñā-śikṣā). 'Stream-enterers', 'once-returners', and 'never-returners' are called śaikṣa as they need to undergo a training. The Arhat-s are called aśaikṣa-s (adepts) because they do not need it. Ānanda lived as a learner (śaikṣa) till the Buddha was alive.

Buddhānusmṛti - A Glossary of Buddhist Terms

Dīgha Nikāya. Mahāparinibbāna. Saṃyutta Nikāya. Padesa.

śaikṣa: Trainee; referring to the ārya-s who are not artha-s,' pertaining to the trainee.

Sarvastivada Abhidharma, Sanskrit-English Glossary, by Bhikkhu KL Dhammajoti

śaikṣa: Trainee; referring to the ārya-s who are not artha-s,' pertaining to the trainee.

Sarvastivada Abhidharma, Sanskrit-English Glossary, by Bhikkhu KL Dhammajoti