c (obsolete|archaic|or|dialectal)(context|usually used with for)because|Because; for.
c (non-gloss definition|Used in comparisons, to introduce the basis of comparison.)
p introduces a comparison, and is associated with comparatives, and with words such as more, less, and fewer. Typically, it seeks to measure the force of an adjective or similar description between two predicates.
a (context|Now|_|chiefly|_|dialectal) At that time; then.