The same word is used with two different meanings.
This is fallacious because the author of the claim confuses the two meanings.
Criminal actions are illegal, and all murder trials are criminal actions, thus all murder trials are illegal. (Here the term "criminal actions" is used with two different meanings.
The sign said "fine for parking here", and since it was fine, I parked there.
All child-murderers are inhuman, thus, no child-murderer is human. This is called "illicit obversion."
A plane is a carpenter's tool, and the Boeing 737 is a plane, hence the Boeing 737 is a carpenter's tool.
Identify the word which is used twice, then show that a definition which is appropriate for one use of the word would not be appropriate for the second use.