What is "Oleo"?

The recipe in my last post refers to the ingredient "oleo".  Grams used this term frequently.  I came to learn that she meant margarine as opposed to butter, but it made me giggle even then as no one else I knew used it.  I decided to use the trusty Internet to learn more about this baking terminology.  Here is what I found:

• From Wikipedia - Oleo is a term used for oils. It is commonly used to refer a variety of things including: margarine...
• From The Free Dictionary by Farlex -  a spread made chiefly from vegetable oils and used as a substitute for butter; margarine