Although tefillin is technically the plural form (the singular being tefillah), it is loosely used as a singular as well. The arm-tefillin, or shel yad, is placed on the upper arm, and the strap wrapped around the arm/hand, hand and fingers; while the head-tefillin, or shel rosh, is placed above the forehead.
Definition of declination. 1 : angular distance north or south from the celestial equator measured along a great circle passing through the celestial poles. 2 : a turning aside or swerving. 3 : deterioration moral declination. 4 : a bending downward : inclination.
The Earthâs magnetic and geographic poles are in different places, and magnetic declination is the angular difference between the direction a compass needle points and the direction to the geographic North Pole. For most of the populated world, this angle is between zero and 30 degrees. Currently, Salt Lake City has a magnetic declination of about 12.5 degrees east (in other words, true north is 12.5 degrees west of the direction a compass needle points), but the angle has been getting smaller over time.