Answer:
Formal language is less personal than informal language. ... Formal language does not use colloquialisms, contractions or first person pronouns such as 'I' or 'We'. Informal language is more casual and spontaneous. It is used when communicating with friends or family either in writing or in conversation.
For close family and friends, you can with your first name or a nickname.
In the word oncology, the root/combining form means tumor. The root/combining form in the word chondrosarcoma means cartilage.