[*] 178. The Supine Stem may be found by dropping -um from the Supine. It is formed by adding t (or, by a phonetic change, s )— [*] a. To the present stem: as, amā-t-um , dēlē-t-um , audī-t-um . [*] b. To the root, with or without ĭ: as, cap-t-um ( capiō , CAP), moni-t-um ( moneō , MON used as root), cās-um (for †cad-t-um, CAD), lēc-t-um (LEG).
[*] Note 1.--By phonetic change dt and tt become s ( dēfēnsum , versum for †dē-fendt-um, †vert-t-um ); bt becomes pt (scrīp-t-um for †scrīb-t-um); gt becomes ct (rēc-t-um for †reg-t-um ).
1[*] Note 2.--The modifications of the present stem sometimes appear in the supine: as, tīnc-t-um ( tingō , TIG), tēn-s-um for †tend-t-um ( ten-d-ō , TEN).
[*] Note 3.--The supine is sometimes from a lost or imaginary verb-stem: as, petī-t-um (as if from †peti-ō, †petī-re, PET).
[*] Note 4.--A few verbs form the supine stem in s after the analogy of verbs in d and t: as, fal-s-um ( fallō ), pul-s-um ( pellō ).