The affix kha optionally may be added without change of sense to a stem ending in añc when it does not mean a point of the compass used in the feminine gender.,
Thus प्राक् or प्राचीनम् \old\, अर्वाक् or अर्वाचीनम्
ew\.
Why do we say \when not denoting a direction in the feminine?\ Observe प्राची दिक् \eastern region\, प्रतीची दिक् \western region.\ Why do we say \a point of the compass\? Other words in the feminine will take this affix. As प्राचीना ब्राह्मणी, अर्वाचीना शिखा ॥ Why do we say \in the feminine\? A direction or दिक् used in any other gender will take this affix. As प्राचीनं दिग्रमणीयम्, उदीचीनं दिग्रमणीयम् ॥,