*ˁbd - to serve (?), to work, to make
(Huehnergard 1995: 276; Kogan 2015: 380)
The meaning “to serve” is probably the original one (cf. Huehnergard 1995:276);
A denominative verb from *ˁabd- rather than vice versa (Kogan 2015: 181)
PCS
*ˁabd- - male slave
(Kogan 2011: 237; Kogan 2015: 181)
*ˁḏr - to help
(Hasselbach–Huehnergard 2007:420; Kogan 2015: 206)
Note that the semantic gap between the meaning “to excuse” in Arabic and “to help” reconstructed for PCS is considerable. See also Arb ˁuḏr- ‘attainment, accomplishing of what one wants, success, victory’. Does this derived noun preserve a more archaic meaning “success” (< “help”), lost elsewhere in Arabic? For the semantic relationship between “help” and “victory, success” cf. Arb. naṣr- (Kogan 2015: 206)
Contra HALOT 834, there is hardly any connection with Hbr. ˁlm ‘to be hidden, concealed.’
PCS
*ˁimm(-a) - together with
(Arakelova 2001:41; Huehnergard 2005:190; Hasselbach–Huehnergard 2007:420; Kogan 2015: 182)
Lipiński (1997:465) derives this preposition from the PS verbal root ‘to be common’. More cautious treatments can be found in Gesenius 1910:297 (”ˁim- (connexion ?) with”) and Tropper 2000:763 (”ˁm /ˁimma/ (Subst. /ˁimm-/? “Gemeinschaft” im Ak.)”).