Definition of "searching"

Einstein's photoelectric equation has been subjected to very searching tests and it appears in every case to predict exactly the observed results.

1916 March, R. A. Millikan, “A Direct Photoelectric Determination of Planck's "h"”, in Physical Review, volume 7, number 3, page 388

‘So you are going out there. Famous. Interesting too.’ He gave me a searching glance, and made another note.

1899 February, Joseph Conrad, “The Heart of Darkness”, in Blackwood’s Edinburgh Magazine, volume CLXV, number M, New York, N.Y.: The Leonard Scott Publishing Company, […], part I, page 201

Her songs take us through many mood changes from lighthearted lovesongs and social commentary to a serious searching for answers and understanding.

1978 April 8, Barb Nesto, “Woman from the West”, in Gay Community News, page 10

Depending on whom you ask, Antony Flew is either a true convert whose lifelong intellectual searchings finally brought him to God or a senescent scholar possibly being exploited by his associates.

2007 November 4, Mark Oppenheimer, “The Turning of an Atheist”, in New York Times‎