| O-1 Visa | Alien with Extraordinary Ability in Sciences, Arts, Education, Business or Athletics. |
| O-2 Visa | Accompanying Alien. |
| O-3 Visa | Spouse or Child of O-1 or O-2. |
| Occupation | For an alien entering the United States or adjusting without a labor certification, occupation refers to the employment held in the country of last legal residence or in the United States. For an alien with a labor certification, occupation is the employment for which certification has been issued. |
| Orphan | The Immigration and Nationality Act provides a definition of an orphan for the purposes of immigration to the United States. A child may be considered an orphan because of the death or disappearance of, abandonment or desertion by, or separation or loss from, both parents. The child of an unwed mother or surviving parent may be considered an orphan if that parent is unable to care for the child properly and has, in writing, irrevocably released the child for emigration and adoption. The child of an unwed mother may be considered an orphan, as long as the mother does not marry (which would result in the child's having a stepfather) and as long as the child's biological father has not legitimated the child. If the father legitimates the child or the mother marries, the mother is no longer considered a sole parent. The child of a surviving parent may also be an orphan if the surviving parent has not married since the death of the other parent (which would result in the child's having a stepfather or stepmother). In order to qualify as an immediate relative, the orphan must be under the age of sixteen at the time a petition is filed on his or her behalf. To enter the United States, an orphan must have been adopted abroad by a U.S. citizen (and spouse, if married) or be coming to the United States for adoption by a citizen. Note: Prospective adoptive parents should be sure that a child fits the definition of "orphan" before adopting a child from another country, because not all children adopted abroad meet the definition of "orphan," and therefore may not be eligible to immigrate to the United States. |
| Out of Wedlock (born out of wedlock) | A child born of parents who were not legally married to each other at that time. Note: Adoptive and prospective adoptive parents of a child who was born out of wedlock in any country should find out whether or not the child has been legitimated. |