Same entry in other lexica. The headword is neuter plural of the rare adjective ἀγαθικός ; outside lexica and grammars, it is attested only in Epicharmus fr. 99 Kaibel, also a neuter plural, which may well have generated these entries.
The glossing adjective σπουδαῖος , translated here as 'excellent', can also mean serious, weighty, morally good, and various other such terms. See sigma 970, also web address 1 for the LSJ entry.