15000 years BC, the Vedas were created. They are the most important scriptures in Hindu history. The Vedas were written in Sanskrit. 

Sanskrit is for the mind what Asanas (= yoga postures) are for the body. It is the language used in most of the ancient Hindu texts. Many academics have spent years deciphering the deeper meaning of many texts such as the Bhagavad Gita, Siva Sutras, or the Yoga Sutras of Patanjali. To date, tons and tons of manuscripts have not even been studied for lack of funds. When the British arrived in India in 1608, they looted many religious sites and brought back hundreds of texts for study. They wrote many commentaries and treatises from what they’ve learned. Nevertheless, when it comes to studying Sanskrit, there are many facts to keep in mind:

Fact # 1: The sacred texts use a lot of allegories and metaphors. It can be seen even in the aesthetics of sacred places in India: deities with 4 heads, characters that are half man, half animal. Should we take them literally or figuratively? This was left to the appreciation of academics who have studied the texts.

Fact # 2: Western culture is extremely different from Hindu culture. All this generates differences in interpretation. You will be able to find hundreds of commentaries for the Yoga Sutras of Patanjali alone. You will also find differences in interpretation here and there. My advice is to not take anything as the absolute truth. Allow the messages and different interpretations to be processed by you time and time again. You will see that the meanings of the Sutras will change internally, and the truth of the message will light up within you.

Fact # 3: How is it possible to be completely impartial when so many words and concepts are unknown? We don't know the life of the interpreter and his or her faculty to remain impartial. While every academic has done their best, that doesn't mean we should take their conclusions at face value.

Fact # 4: Sanskrit is a living language. It reads like a poem. Therefore, Sanskrit texts lose their meaning in translation. Your best bet would be to learn Sanskrit to truly integrate the beautiful messages conveyed by the scriptures. As a matter of fact, Sanskrit affects the physical body and can purify the blood, bone, and bone marrow when pronounced properly. It is even said to cure diseases.

Now that the basics have been established, you can find a lexicon below with the most common Sanskrit terms in the Yoga Sutras of Patanjali. If you continue studying the texts you will see these terms so often you will know them by heart. Remember that each of these terms has many synonyms, and their meaning is much broader than the translation. Keep an open mind, and let the words move your senses and your subconscious.

From A to Z 

Ahamkara: the I-Maker or I-Former (I am)

Asana: comfortable seated posture

Asteya: absence of greed

Atman: the supreme self

Avidya: ignorance

Ayurveda: science of life

Brahmacharya: control of the Creative energy

Buddhi: Intellect

Citta: thinking consciousness, memory box

Dharana: concentration

Dhyana: meditation

Jnanendriyas: the 5 lower sense organs (the ears, the eyes, the nose, the tongue, the skin)

Karmendriyas: the 5 organs of action (reproduction, speech, elimination, feet, and hands)

Mahabhutas: the 5 Gross elements (air, fire, ether, water, earth)

Manas: the mind

Mantra: a word or a sound repeated 

Nirodhah: inhibition or suppression

Prakriti: matter, constitution, limited self 

Pratyahara: withdrawal of the senses

Purusha: unlimited consciousness, absolute, the higher self

Rajas: active qualities of Prakriti

Samadhi: enlightenment

Samkhya: orthodox philosophical system of the Hindu culture

Satya: Truth

Sattva: pure qualities of Prakriti

Tamas: inactive qualities of Prakriti

Tanmatras: subtle elements

Tantra: Hindu philosophical and mystical system

Vrtti: fluctuations

If there are any other terms that you would like me to add, leave a comment below and I will make sure to add them.