स्तन्भु

taking स्तम्भ as related concept
स्तन्भु = ष ठ न भ उ
pointed hollow ground pull steadyoutward

OR
स्तन्भु = स त न भ उ
do pull boat/steady (inside) furrow afloat

स्तुन्भुँ = do pull boat/steady do float (inside) furrow

स्कन्भुँ = do pull boat/steady, hand held (inside) furrow

स्कुन्भुँ = do pull boat/steady, do hand-held (inside) furrow

स्कुञ्भ्यः = net steady/boat connect, do hand-held (inside) furrow

commentary
स्कुञ् is not सौत्र धातु but included herebecause in 3.1.82 can be interpreted as a whole वर्ण समास including भ्य.