The suffix [-oid] originates from the Greek [oeides], meaning "similar to", "like", or "shaped like". This suffix can be found the the medical terms [sigmoid] meaning "similar or shaped like a sigma"; [sphenoid], meaning "shaped like a wedge"; [cricoid], meaning "shaped like a ring", and [arytenoid] also from the Greek [arytaina], meaning "similar to a ladle".

This suffix is also used in daily conversation, as the following examples illustrate:

• Android - "similar to a human", from the Greek [andros] human
• Anthropoid - similar to a man, from the Greek [anthropos], "man"
• Asteroid - "similar to a star", from the Greek [aster], "star"
• Arachnoid - "similar to a spider", from the latin [arachnid], spider. It refers to the spider-web look of this menynx