Nonacrophonic

Children may have more to gain from acrophonic first letters than from nonacrophonic letters since it is easier to recognize /b/ in 'bear' than /es/ in 'stone.'

Source: wiktionary

Some languages have only acrophonic letter names, and others have some phonetically iconic but nonacrophonic names as well.

Source: wiktionary

Letter-related factors included letter-name structures (e.g., CV or VC letter-name structures versus nonacrophonic letter names) and letter–sound ambiguity (e.g., letters that are associated with more than one sound or that share a sound with another letter).

Source: wiktionary