A more thorough explanation:

Term: in essentialibus
Definition: In Scots law, this term means "in the essential parts." If there is an error in an important term of a legal document, such as a deed, it can be very serious and may make the document invalid.
Example: If a deed for a house mistakenly lists the wrong address, it could be considered an error in an essential term and the deed may not be legally binding. This is why it's important to carefully review legal documents before signing them.