quantum English · revision 10278

+ {{infobox|confidence=established|formation=borrowing|attested=1567|origins=la quantum}}

+

+ ==Pronunciation==

+ * IPA: /ˈkwɒntəm/ ''(UK)''; /ˈkwɑntəm/ ''(US)''^(Wiktionary)

+

+ ==Etymology==

+ It is [[bor|la|quantum|t=how much, as much as]], the neuter singular of quantus, how great (see [[quantity]]).^(Barnhart 1988)^(Etymonline)^(MWU 2024)

+

+ ==Earliest recorded meaning==

+ A sum or amount: 1567 in Merriam-Webster, 1619 in Barnhart and the OED (in Purchas' ''Microcosmus''), the 1610s in Etymonline.^(MWU 2024)^(Barnhart 1988)^(OED 1989)^(Etymonline)

+

+ ==Semantic evolution==

+ One's share or portion is from 1649.^(OED 1989) Max Planck introduced the word into physics directly from Latin in 1900, for the minimum amount of a quantity that can exist, and Einstein reinforced it in 1905;^(Etymonline)^(Cresswell 2021) the physical sense is first recorded in English in 1910.^(Barnhart 1988)^(OED 1989) ''Quantum theory'' is from 1912 and ''quantum mechanics'' from 1922.^(Etymonline) A ''quantum leap'' (mid-20th century), strictly a tiny change of state, is used popularly for a sudden large advance.^(Cresswell 2021)

+

+ ==Timeline==

+ * 1567 – an amount.^(MWU 2024)

+ * 1649 – a share.^(OED 1989)

+ * 1910 – a unit of energy (physics).^(Barnhart 1988)

+ * 1912 – quantum theory.^(Etymonline)

+ * 1922 – quantum mechanics.^(Etymonline)

+

+ ==Modern meaning==

+ ===Noun===

+ # ''(physics)'' The smallest amount of a physical quantity, such as [[energy]], that can exist independently.^(AHD)^(Collins 2023)

+ # A quantity or amount, especially a specified one.^(AHD)^(Collins 2023)

+ # A specified portion or share.^(AHD)

+

+ ===Adjective===

+ # Sudden and significant, as in ''a quantum increase''.^(AHD)

+

+ ==Word family==

+ * [[quantize]]

+

+ ==Related words==

+ * [[quantity]]

+ * [[quanta]]

+ * [[quantify]]

+

+ ==Usage notes==

+ Word Origins notes the paradox that a ''quantum leap'', used for a dramatic advance, in physics describes a very small change.^(Cresswell 2021)

+

+ ==References==

+ {{reflist}}