Jacob's thigh was disabled by the Angel, to show the patriarch that his prevalence was through his faith and prayer, not through force, Genesis 32:25-31. Smiting the thigh was a gesture of self-condemnation and grief, Jeremiah 31:19 Ezekiel 21:12.
In general, a datum is a base elevation used as a reference from which to reckon heights or depths. A tidal datum is a standard elevation defined by a certain phase of the tide.
Datum is, from its Latin origin, a singular form of data, and may refer to a single item of data. 1 Singular data point. 1  Geodetic datum, a standard position or level that measurements are taken from in geographic surveying. 2  Datum reference, in carpentry, metalworking, needlework, geometric dimensioning and tolerancing. 3  Chart datum, level of water depth on a nautical chart. Datum or datum point, a (possibly arbitrary) reference baseline or point from which scientific measurements are made (from a Latin meaning of datum as a given, i.e. an accepted fact)