Namaskar or Namaskara or Namaskaram?

In Sanskrit, the word namaskar is correctly written as नमस्कार (IAST: namaskāra).  It is a masculine noun derived from the root words namas (bow/obeisance) and kāra (action). 

According to standard Sanskrit grammar and the provided context:

• The correct spelling uses the vowel sign आ (long ‘a’) at the end, making it नमस्कार rather than नमस्कर. 
• The full form with the visarga (the two dots indicating a final ‘s’ sound) is नमस्कारः (namaskāraḥ). 
• It is distinct from नमस्ते (namaste), which uses the root namas and the dative pronoun te (you). 

While नमस्य (namasya) or नमो (namo) are also used in specific grammatical contexts or compounds, नमस्कार is the standard term for “salutation” or “greeting.” 

In Sanskrit, namaskaram is written as नमस्कारम् (IAST: namaskāram). 

The term is a masculine noun derived from the root namas (bow/obeisance) and kāra (action), with the -am ending indicating the accusative singular case. While often used interchangeably with namaste in modern greetings, namaskāram specifically denotes the act or offering of salutation.