Samyama is defined in the Yoga Sutras of Patanjali verses 3.1 through 3.6 as follows where the Sanskrit in Devanagari and IAST were sourced from http://alanlittle.org/yoga/patanjali.html#III and the English from B.K.S. Iyengar (1993: pp. 178–183):
देशबन्धश्चित्तस्य धारणा ॥ १॥ deśabandhaścittasya dhāraṇā .. 1.. Fixing the consciousness on one point or region is concentration (dhāraṇā). तत्र प्रत्ययैकतानता ध्यानम् ॥ २॥ tatra pratyayaikatānatā dhyānam .. 2.. A steady, continuous flow of attention directed towards the same point or region is meditation (dhyāna). तद् एवार्थमात्रनिर्भासं स्वरूपशून्यम् इव समाधिः ॥ ३॥ tad evārthamātranirbhāsaṃ svarūpaśūnyam iva samādhiḥ .. 3.. When the object of meditation engulfs the meditator, appearing as the subject, self-awareness is lost. This is samādhi. त्रयम् एकत्र संयमः ॥ ४॥ trayam ekatra saṃyamaḥ .. 4.. These three together [dhāraṇā, dhyāna and samādhi] constitute integration or saṃyama. तज्जयात् प्रज्ञालोकः ॥ ५॥ tajjayāt prajñālokaḥ .. 5.. From mastery of saṃyama comes the light of awareness and insight. तस्य भूमिषु विनियोगः ॥ ६॥ tasya bhūmiṣu viniyogaḥ .. 6.. Saṃyama may be applied in various spheres to derive its usefulness.