What is the meaning of L-?

deprecated notation for levorotatory (versus modern notation, (−)).

Alternative form of il-

the l- classifier or valence-change prefix, a detransitivizing prefix of active verbs that modifies the transitivity or valence and grammatical voice of a verb, and occurs in most passive, mediopassive, reflexive, and reciprocal verbs that are derived from verbs with a ł- classifier

Source: wiktionary.org