A "column object" is an entity that can be used as a column in an Oracle table.
Column objects usually consist of columns defined with predefined types.
SQL> --CREATE a TABLE with the Column Type in It
SQL>
SQL> CREATE OR REPLACE TYPE ADDRESS_OBJ as OBJECT(
2 street VARCHAR2(20),
3 city VARCHAR2(20),
4 state CHAR(2),
5 zip CHAR(5))
6 /
Type created.
SQL>
SQL> CREATE TABLE emp (
2 empno NUMBER(3),
3 name VARCHAR2(20),
4 address ADDRESS_OBJ)
5 /
Table created.
SQL>
SQL> drop table emp;
Table dropped.
SQL> drop type ADDRESS_OBJ;
Type dropped.
SQL>