In Jainism, the term "16 Akshari Vidya" (षोडशाक्षरी विद्या) refers to a sacred mantra comprising sixteen syllables (aksharas). This mantra is considered very powerful and is traditionally associated with spiritual protection, success, and the removal of obstacles. It is most commonly found in the context of Jain tantric and ritualistic practices, particularly within the Digambara tradition, though some Śvetāmbara texts also reference it.

The mantra itself is as follows:

णमो अरहंताणं, णमो सिद्धाणं, णमो आयरियाणं, णमो उवज्झायाणं

This is the Namokar Mantra (also known as Navkar Mantra), but when counted as a 16-syllable mantra specifically, the focus is on a condensed form, sometimes referred to as:

"णमो अरिहंताणं, णमो सिद्धाणं"

Each syllable is believed to carry immense spiritual potency.

Some key points about 16 Akshari Vidya in Jainism:

• It is often invoked for spiritual well-being, protection from negative influences, and the accomplishment of desires (siddhi).
• Many traditional Jain texts describe the ritualistic method of its recitation and worship, including the use of specific yantras (mystical diagrams) and puja (worship) procedures.
• The knowledge and proper use of the 16 Akshari Vidya is traditionally passed down by gurus to deserving disciples.
• It is considered one of the most potent "vidyas" (mystical knowledge or techniques) in Jain tantric tradition.

References:

• "Jain Tantra Vidya," by Pandit Todarmal Smarak Trust
• "Jain Mantra Sadhana" (various texts)
• Jain Agamas and commentarial literature (especially those discussing mantra and vidya)

If you are seeking the mantra for recitation or for a specific ritual purpose, it is always recommended in Jainism to do so under the guidance of a knowledgeable Jain monk (sadhu/sadhvi) or a learned acharya, as proper understanding and faith are considered essential for its efficacy.