Yogah (योगः) means the act, process or result of:

1. joining or connecting one entity to another,
2. merging one entity into another,
3. applying one entity to another,
4. implementation of an entity or idea or person.

It is derived from the Sanskrit root ‘yuj’ (युज्).

The word and its verb forms are widely used in a variety of meanings in Sanskrit and Indian languages. Examples:

• udyoga (उद्योग:) — production, endeavor, business, job, etc.
• viyoga (वियोगः) — separation, termination, divorce, etc.
• Ayoga (आयोगः) — commission, committee, etc.
• niyoga (नियोगः) — engagement, commitment, support, etc.
• prayoga (प्रयोगः) — experiment, implementation, handle, etc.
• upayoga (उपयोगः) — utility, use (noun & verb)
• prayojanam (प्रयोजनम्) — purpose, rationale
• Ayojanam/prAyojanam (आयोजनम्/प्रायोजनम्) — setup, prepare, sponsor, plan or execute (an event), etc.
• yogya (योग्यः) — well-suited, fit (for a job or position)
• ayogya (अयोग्यः) — ill-suited, unfit, useless
• yukta (युक्तः) — appropriate, proper, adequate
• yukti (युक्तिः) — clever idea, ruse, smart plan, etc.
• Ayukta (आयुक्तः) — appointed (to an official position), selected, chosen, an officer (noun), etc.
• upAyukta (उपायुक्तः) — sub-officer, underling, etc.

Of course, the meaning that is most popular today throughout the world is the spiritual meaning of merging one’s individual consciousness to a universal consciousness; or other variations of what is being merged into what (for example, “state of being”, or “existence”, etc.)

This spiritual meaning existed way back in the Rig Veda itself.

Two examples from Rig Veda:

1. RV 5.46.1:

हयो न विद्वान् अयुजि स्वयं धुरि तां वहामि प्रतरणीमवस्युवम्।

नास्या वश्मि विमुचं नावृतं पुनर्विद्वान् पथः पुरएत ऋजु नेषति ॥

“hayo na vidvAn ayuji svayam dhuri tAm vahAmi prataraNIm avasyuvam |

nAsyA vashmi vimucam nAvRtam punarvidvAn pathah puraeta Rju neShati ||”

“Like a knowing horse, I have joined myself to the “world cycle” and I carry that which is protective and gives salvation. I do not desire a release from this, nor do I desire a continuation. The wise, all-knowing Atman, knower of the path, the leader will lead me straight.”

This pretty much summarizes all of Vedanta and all of the Bhakti teachings that came in the later times.

2. RV 5.81.1:

युञ्जते मन उत युञ्जते धियो विप्रा विप्रस्य बृहतो विपश्चितः ।

“yu~njate mana uta yu~njate dhiyo viprA viprasya bRhato vipashcitah |”

“The wise humans (rishis) join their minds and intellect to the bigger wise, the all-knowing.”

This is very interesting. First of all, this mantra pretty much describes the process of yogic samAdhi. The wise persons (rishis) are trying to merge their consciousness and states of being into the universal consciousness.

Second important point to note is that both the humans and the deity are called “wise”. So there is no essential difference in substance between the human aspirant and the divine. The only difference is that the deity is called the “bigger wise”. So in calling them both “wise”, we see the concept of non-duality (advaita). And in calling the deity the “bigger wise”, we see hints of the concept of qualified non-duality (vishiShTAdvaita).