Sedley's paper on On Nature Book 28 addresses some of that about language and definitions
Plus see:
[ U258 ]
Erotianus, Glossary of Hippocrates, Preface, [p. 34, 10 Klein]: For if we are going to explain the words known to everybody, we would have to expound either all or some. But to expound all is impossible, whereas to expound some is pointless. For we will explain them either through familiar locutions or through unfamiliar. But unfamiliar words seem unsuited to the task, the accepted principle being to explain less known things by means of better known things; and familiar words, by being on a par with them, will be unfamiliar for illuminating language, as Epicurus says. For the informativeness of language is characteristically ruined when it is bewitched by an account, as if by a homeopathic drug.
[U92]Scholiast on Dionysius Thrax {"Dionysius the Thracian"}, The Art of Grammar, [p. 660, 25 Bekk.]: And although Epicurus always made use of general outlines {of the senses of words}, he showed that definitions are more worthy of respect by using definitions instead of general outlines in the treatise On Nature; for he used definitions when he divided the totality {of existence} into the atomic and the void, saying that "the atomic is a solid body which has no share of void included in it; void is an intangible nature," i.e., not subject to touch.
[U352] Quintilian, Institutio Oratoria, VII.3.5: A man who denies that god is a "spirit diffused through all the parts of the world" {a Stoic definition} would not be saying that it is mistaken to call the world divine, as Epicurus would, for he gave God human form and a place in the spaces between worlds.
[ U451 ]
Antiochus of Ascalon, by way of Clement of Alexandria, Miscellanies II.21 p. 179.36: These Cyrenaics reject Epicurus’ definition of pleasure, i.e., the removal of pain, calling that the condition of a corpse; because we rejoice not only on account of pleasures, but companionships and distinctions; while Epicurus thinks that all joy of the soul arises from previous sensations of the flesh.