Words That Start With OS

69 words Words by letter Checked 9 Oct 2026

Here are 69 words that start with os, from everyday words to rare ones that are still valid in word games. Common words come first with a short meaning, then the words are grouped by length, which helps with Wordle and crossword clues.

Words starting with os: 69
Most used: ostensibly
Shortest: ose
5 letter words: 2

Common words that start with os

#	Word	Meaning	Letters
1	ostensibly	from appearances alone; ; ; -Thomas Hardy	10
2	ostrich	a person who refuses to face reality or recognize the truth (a reference to the popular notion that the...	7
3	osteoporosis	abnormal loss of bony tissue resulting in fragile porous bones attributable to a lack of calcium	12
4	oscillation	the process of oscillating between states	11
5	oscillator	generator that produces sonic oscillations or alternating current	10
6	oscillations	the process of oscillating between states	12
7	osprey	large harmless hawk found worldwide that feeds on fish and builds a bulky nest often occupied for years	6
8	osmosis	(biology, chemistry) diffusion of molecules through a semipermeable membrane from a place of higher...	7
9	oscillating	be undecided about something; waver between conflicting positions or courses of action	11
10	osteoarthritis	chronic breakdown of cartilage in the joints	14
11	ospreys	large harmless hawk found worldwide that feeds on fish and builds a bulky nest often occupied for years	7
12	ostentatious	intended to attract notice and impress others	12
13	oscillators	generator that produces sonic oscillations or alternating current	11
14	ostracized	expel from a community or group	10
15	ostensible	appearing as such but not necessarily so	10
16	osmotic	of or relating to osmosis	7
17	ostriches	a person who refuses to face reality or recognize the truth (a reference to the popular notion that the...	9
18	oscillate	be undecided about something; waver between conflicting positions or courses of action	9
19	oscilloscope	electronic equipment that provides visual images of varying electrical quantities	12
20	ostracism	the state of being banished or ostracized (excluded from society by general consent)	9
21	osteopathy	therapy based on the assumption that restoring health is best accomplished by manipulating the skeleton and...	10
22	oscillates	be undecided about something; waver between conflicting positions or courses of action	10
23	oscillatory	having periodic vibrations	11
24	ostracised	expel from a community or group	10
25	ossified	become bony	8
26	ostentatiously	with ostentation; in an ostentatious manner	14
27	osteomyelitis	an inflammation of bone and bone marrow (usually caused by bacterial infection)	13
28	ostentation	a gaudy outward display	11
29	oses	a mouth or mouthlike opening	4
30	osteosarcoma	malignant bone tumor; most common in children and young adults where it tends to affect the femur	12
31	osteopath	a therapist who manipulates the skeleton and muscles	9
32	ossification	the developmental process of bone formation	12
33	osmium	a hard brittle blue-grey or blue-black metallic element that is one of the platinum metals	6
34	oscillated	be undecided about something; waver between conflicting positions or courses of action	10
35	ostomy	surgical procedure that creates an artificial opening for the elimination of bodily wastes	6
36	osmund	any fern of the genus Osmunda: large ferns with creeping rhizomes	6
37	osteoblasts	a cell from which bone develops	11
38	ossuary	any receptacle for the burial of human bones	7
39	ossa	a mouth or mouthlike opening	4
40	osseous	composed of or containing bone	7
41	oscilloscopes	electronic equipment that provides visual images of varying electrical quantities	13
42	osteoclasts	cell that functions in the breakdown and resorption of bone tissue	11
43	ostler	someone employed in a stable to take care of the horses	6
44	ostracize	expel from a community or group	9
45	ostinato	a musical phrase repeated over and over during a composition	8
46	ossicles	a small bone; especially one in the middle ear	8
47	osteology	the branch of anatomy that studies the bones of the vertebrate skeleton	9
48	ostracods	tiny marine and freshwater crustaceans with a shrimp-like body enclosed in a bivalve shell	9
49	osteopaths	a therapist who manipulates the skeleton and muscles	10
50	osteoblast	a cell from which bone develops	10

3 letter words that start with os

4 letter words that start with os

oses
ossa

5 letter words that start with os

ostia
osier

6 letter words that start with os

osprey
osmium
ostomy
osmund
ostler
ostium
osmose

7 letter words that start with os

ostrich
osmosis
ospreys
osmotic
ossuary
osseous

8 letter words that start with os

ossified
ostinato
ossicles
osteitis
ostracod

9 letter words that start with os

ostriches
oscillate
ostracism
osteopath
ostracize
osteology
ostracods
ossuaries

10 letter words that start with os

ostensibly
oscillator
ostracized
ostensible
osteopathy
oscillates
ostracised
oscillated
osteogenic
osteopaths
osmolality
osteoblast
osteoclast
osmolarity

11 letter words that start with os

oscillation
oscillating
osteopathic
oscillators
oscillatory
ostentation
osteoblasts
osteoclasts
ostracizing
osmotically

12 letter words that start with os

osteoporosis
oscillations
ostentatious
oscilloscope
osteosarcoma
ossification
osteogenesis
osteoporotic
osteological
osteomalacia

Filter all 69 words that start with os

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All words that start with O
5 letter words that start with O
Other starts: oa, ob, oc, od, oi, ol, om, on, oo, op, or, ot

Questions people ask

How many words start with os?

This list has 69 words starting with os, all from a standard word-game dictionary and all seen in real English text.

What are common words that start with os?

ostensibly, ostrich, osteoporosis, oscillation, oscillator, oscillations, osprey, osmosis.

What 5 letter words start with os?

ostia, osier.

Source: the ENABLE word list (a public-domain dictionary used for word games), ranked by how often each word appears in English text (the open wordfreq project), with short meanings from Princeton WordNet. Offensive words are left out.