OD

UK: 'OD': /ˌəʊˈdiː/; 'od': /ɒd/

US: /ˈoʊˈdi/

US: 'OD': (ō′dē′); 'od': (od, ōd)

WordReference Random House Learner's Dictionary of American English © 2026

OD /ˈoʊˈdi/   n., pl. ODs or OD's, v., OD'd or ODed, OD'•ing. 
n. [countable]

1. Drugs an overdose of a drug, esp. a fatal one.
2. Drugs a person who has become seriously ill or has died from a drug overdose.

v. [no object]

3. Drugs to take a drug overdose.
4. Drugs to die from a drug overdose.
5. to have or take too much of something:
   I was OD'ing on caffeine.

Collins Concise English Dictionary © HarperCollins Publishers::

OD / ˌəʊˈdiː/ noun

1. an overdose of a drug

verb (OD's, OD'ing, OD'd)

1. (intransitive) to take an overdose of a drug

Etymology: 20th Century: from o(ver)d(ose)

OD abbreviation

1. Officer of the Day
2. Also: o.d. olive drab
3. Also: O/D on demand
4. overdrawn
5. ordnance datum
6. outside diameter

WordReference Random House Unabridged Dictionary of American English © 2026

od  (od, ōd), n. 

1. a hypothetical force formerly held to pervade all nature and to manifest itself in magnetism, mesmerism, chemical action, etc.

Also, odyl, odyle. 

• arbitrary name coined by Karl von Reichenbach (1788–1869), German scientist 1840–50

Od  (od), interj. [Archaic.]

1. a shortened form of "God'' (used interjectionally and in minced oaths).

Also, 'Od, Odd. 

• 1590–1600

OD  (ō′dē′), n., pl. ODs or OD's, v., OD'd or ODed or OD'ed, OD'ing or OD•ing. 
n. 

1. Drugs, Military an overdose of a drug, esp. a fatal one.
2. Drugs a person who has taken an overdose of a drug, esp. one who has become seriously ill or has died from such an overdose.

v.i. 

3. Drugs, Military to take an overdose of a drug.
4. Drugs to die from an an overdose of a drug.
5. to have or experience an excessive amount or degree of something.

• 1955–60

OD, 

1. See officer of the day. 
2. Old Dutch.
3. Ordnance Department.
4. outside diameter.

od, 

1. on demand.
2. outside diameter.
3. outside dimensions.
4. overdraft.
5. overdrawn.

OD., 

1. Old Dutch.

O.D., 

1. Doctor of Optometry.
2. Drugs (in prescriptions) the right eye.
• Latin oculus dexter
3. Military See officer of the day. 
4. Old Dutch.
5. (of a military uniform) olive drab.
6. Naval Terms ordinary seaman.
7. outside diameter.
8. overdraft.
9. overdrawn.

o.d., 

1. Drugs (in prescriptions) the right eye.
• Latin oculus dexter
2. Military olive drab.
3. on demand.
4. outside diameter.

Collins Concise English Dictionary © HarperCollins Publishers::

od / ɒd əʊd/, odyl, odyle / ˈɒdɪl/ noun

1. a hypothetical force formerly thought to be responsible for many natural phenomena, such as magnetism, light, and hypnotism

Etymology: 19th Century: coined arbitrarily by Baron Karl von Reichenbach (1788–1869), German scientist

ˈodic adjective