استسرّ
1.
He, or it, became concealed; or he,
or it, concealed himself or itself: (K:) it (a thing, or an affair,) became hidden or concealed or secret: (A, Msb:) it (the moon) became concealed (S, M, A, TA) by the light of the sun, (TA,) [i. e. by its proximity to the sun,] for one night, or for two nights. (AO, S.)
2.
استسرّهُ
He took extraordinary pains in concealing it, or keeping it secret. (TA.)
3.
See also 5, in four places.
4.
اِسْتَسَرَّنِى
He revealed to me his secret. (TA.)
5.
See also 1; and see 6, last sentence.