Here are simple, respectful greetings you can offer to a muni ( Jain monk):

• Namo Arihantanam.

Meaning: I bow to the Arihants (those who have conquered inner enemies and realized enlightenment).

• Namo Siddhaanam.

Meaning: I bow to the Siddhas (liberated souls).

• Namo Ayariyanam.

Meaning: I bow to the Ariyas (great teachers and revered teachers who have attained right knowledge).

• Namo Uvajjayanam.

Meaning: I bow to the Upadhyayas (spiritual teachers who guide the Jain community).

• Namo Loe Savva Sahunam.

Meaning: I bow to all living beings (a universal gesture of respect and compassion).

If you prefer a single, widely used greeting:

• Namokar Mantra is a central salutation in Jainism and is appropriate as a respectful greeting to muni. It encapsulates reverence to Arihants, Siddhas, Acharyas, Upadhyayas, and Sadhus.

Notes:

• These forms are common to both Digambar and Shwetambar traditions, though exact usage can vary by community and context.
• When greeting a muni in person, a gentle bow with folded hands (namaste) is also appropriate in addition to these phrases.