Each of the following extracts from EDGAR exhibits the same problem:
For purposes of this Agreement, “Eligible Plan Assets” mean total Plan Assets (including assets invested in American Funds and other mutual funds or investment options approved for use in PlanPremier), excluding …
“Moral Rights” mean any rights to claim authorship of or credit on an Assigned Inventions …
For purpose of this Agreement, the “Products” mean the specified Ultra Sonic motors as described in Exhibit A and its modified version agreed in writing by the Parties.
Each example uses mean instead of means. The drafter presumably thought because the defined term is in the plural, the verb should be plural too. But that misconstrues the function of the defined term in an autonomous definition: the definition says what the word or phrase means, not what each individual component means.
I don’t know how often this occurs, but I saw an instance of it today in a client’s contract, and that makes it real enough for me to write about it.