In astrology, there are certain sensitive points in a birth chart that are considered unfavorable for auspicious beginnings or important life events.
Sthula Nakshatra
Count the nakshatras from the nakshatra occupied by the Sun in your birth chart to Mula Nakshatra. Now count the same from Mula Nakshatra, the nakshatra arrived at is Sthula. Sthula means "gross or bulky" and any events started under Sthula nakshatra face some obstacles/interruptions but it may not ruin the event.
Kantaka Nakshatra
Count the nakshatras from the nakshatra occupied by Mars in your birth chart to Mula Nakshatra. Now count the same from Mula Nakshatra, the nakshatra arrived at is Kantaka. Kantaka means "thorn-like protrusions" and any events started under kantaka nakshatras could cause some pain or negative
effects, but it may not ruin the event.
Kantaka Sthula Nakshatra
Count the nakshatras from the nakshatra occupied by the Sun in your birth chart to Mula Nakshatra. Count the nakshatras from the nakshatra occupied by Mars in your birth chart to Mula Nakshatra. Add them both.
Now count the same from Mula Nakshatra, the nakshatra arrived at is Kantaka Sthula. Kantaka sthula means "massive thorn" and events started under this nakshatra could have a lot of negative consequences and should be avoided unless there are other strong factors that are supportive.