ob-⁵ +

1. To see, watch, perceive, or notice: "He observed the passersby in the street."
2. To regard with attention; especially, so as to see or learn something: "I want you to observe her reaction to the judge's question."
3. To watch, view, or note for a scientific, official, or other special purpose: "She wanted to observe the eclipse of the moon."

1. To dominate or preoccupy the thoughts, feelings, or desires of (a person); beset, trouble, or haunt persistently or abnormally: "Suspicion obsessed him."
2. To think about something unceasingly or persistently.
3. To occupy someone's thoughts constantly, compulsively, and exclusively: "The desire for vengeance obsesses her."
4. Etymology: "To besiege", from Latin obsessus, past participle of obsidere, "besiege, occupy". Literally, "sit opposite to", from ob, "against" plus sedere "to sit". Of evil spirits, "to haunt", is from 1540. Obsession was originally (1513), "the act of besieging", then "hostile action of the devil or an evil spirit" (1605). The meaning "persistent influence or idea" is first recorded in 1680.

1. Old; no longer in use, valid, or fashionable.
2. Superseded by something newer, although possibly still in use.
3. A description of a part or organ of an animal or plant that is undeveloped or no longer functional.
4. A reference to words, equipment, etc., no longer in use; gone into disuse; disused or neglected (often by preference for something newer, which replaces the subject).
5. Synonyms of obsolete: ancient, antiquated, antique, archaic, disused, neglected, old, old-fashioned, out of date, discontinued, defunct, outmoded, and superannuated.
6. Etymology: from Latin obsoletus, "grown old, worn out"; past participle of obsolescere, "to wear out, to grow old, to fall into disuse"; probably from ob-, "away" + solere, "to be used to, to be accustomed".

1. No longer in use or no longer useful; of a kind or style no longer current; old-fashioned.
2. With reference to a plant or animal part, indistinct or imperfect as compared with a corresponding part in related organisms; vestigial (bodily part or organ that is small and degenerate or imperfectly developed in comparison to one more fully developed in an earlier stage of the individual, in a past generation, or in closely related forms).

A condition in which something is out of date and is no longer in current use.

1. To take or fill up (space, time, etc.): "I occupied my evenings reading novels."
2. To engage or employ the mind, energy, or attention of: "He will occupy the children with a game while I prepare dinner."
3. To be a resident or tenant of; to dwell in: "We occupied the same house for 20 years."
4. To take possession and control of (a place), as by a military invasion.
5. To hold (a position, office, etc.).
6. Etymology: "to take possession of"; also, "to take up space or time, to employ (someone)"; from Old French occuper; from Latin occupare, "to take over, to seize, to possess"; which came from Latin, ob, "over" + a form of capere, "to grasp, to seize".