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Webster 1913 Edition

Adj.

Generating or containing pus; purulent.

Full of substance or matter; important.

B. Jonson.

Adj.

Purulent; generating pus; as a mattery cough.

mattery ‎(comparative more mattery, superlative most mattery)

pussy, purulent (containing or secreting pus)
(obsolete) Full of substance or matter; important.
(Can we find and add a quotation of Ben Jonson to this entry?)