Here are my YOGA defintions. 

Yoga - the state of -

…is the union with God, the Self-Realised, the Fully Enlightened state(s) of Being.

Yoga is the Indian / Sanskrit name for the Spiritual Divine Union with God and could be used to describe the same states in all spiritual practice, under other names, that expresses the ultimate perfection, the Divine, the Awakening, the Union of the individual self with Higher Consciousness /Creator/God/Universal Spirit/Divine Mother/Divine Father/Higher Self.

Yoga - the path of spiritual practice -

…is the path to Yoga, to God, with ancient origins in the spiritual traditions and teachings of great Sages, Masters, Divine Teachers who walked the Earth and shared their wisdom in what we know as the sub-continent of India. Those Spiritual Traditions and Teachings also have an intimate connection with what is today the Religions of India, especially Hinduism.

There are many types of Yoga Spiritual Practice.

Karma Yoga (Voluntary Service - often to the Guru),

Bhakti Yoga (Devotional Yoga through ritual, song, disciple-ship to God and Guru),

Jnana Yoga (Intellectual / Spiritual Study and meditation),

Raja Yoga (Mastering Energy for Meditation and Breath Practice)

...to name a few main types of Yoga Practice and philosophies.

Each type has many sub-divisions, sub-cultures with different methods, masters, philosophies and styles of Yoga practice. Many schools of Yoga today may have aspects of all or many of the main types of Yoga mentioned above or be specialised to one narrower path of practice. The defintions above are in no way complete and yet shows the great diversity of Practice in Yoga.  There is something for everyone in this vast menu of Spiritual Yoga Practice offering.

Of these methods YogaMonks is part of the Hatha Yoga Practice Paths with roots in Raja, Tantra, and Kriya Yoga traditions. 

Most Hatha Yoga schools/styles/methods in modern yoga practice have aspects of all the main types of Yoga, emphasised more or less depending on the main theme or cultivation within the techniques/methods. There is an aspect of Karma (voluntary service) Yoga, Devotional Practices (Bhakti), Song and Chanting, Prayer and Rituals, Study of Scripture (Jnana) and working with and through the intellect, as well as connecting with the physical body to integrate and elevate the human experience with Spirit (Tantra, Kundalini).  

 Yoga - the Process of -

I find the greatest gift to daily life through yoga is that it is a path towards freedom. I have been obsessed by freedom since a very young age. With spiritual practice, done daily in doses, we give ourselves the best conditions towards overcoming our blocks, limitations, hindrances to fully living and fully being here.

Yoga is a process of expansion through integrity, of dissolving blocking boundaries and setting up healthy ones, of self-study and growth into human being-ness, of reaching for higher vibration and consciousness, of healing oneself of illusion and becoming more aware and open to truth. 

Expansion of consciousness is a process of enlightenment. We move from one dimension of being to another, from one light level to another, from darkness to light.

Other definitions of Yoga:

Yoga, the word itself, translates to: union, connection, one-ness, to bring together, to yoke, to unite. 

Yoga is the direct experience of effortless being. (unknown source)

Yoga is the cessation of the fluctuations of the mind. (Patanjali - Yoga Sutras)

In the below somewhat limited dictionary definition you see the dualistic approach to Yoga.

Merriam Webster

yo·​ga | ˈyō-gə 

Definition of yoga

1

capitalized : a Hindu theistic philosophy teaching the suppression of all activity of body, mind, and will in order that the self may realize its distinction from them and attain liberation

2

: a system of physical postures, breathing techniques, and sometimes meditation derived from Yoga but often practiced independently especially in Western cultures to promote physical and emotional well-being.

When I teach the subject of Yoga in my teacher trainings or practitioner courses one of the things we address are these delicious definitions of what or who Yoga is. We aim to put our own practice into the context of what Yoga is and the history and evolution of the practices of Yoga, from where it was to what it is now. Then we leave it in order to go deeper into the practice itself. 

See further Scrolls: Hatha Yoga, Dualistic/Non Dualistic, Energy 

For an A-Z overview of the Scrolls to keep scrolling at your own devise, go here.