I was reading a novel that used the term moral fiber - defined as strength of character - the other day and it occurred to me that it was a somewhat strange conjunction of terms. It sort of conjured up images of 'the stuff morality is made of'; but morality being an intangible idea it's not usually made up of tangible fibers…

I found myself wondering how it originated.

  • Ngram finds credible uses from the 1860s.
    – Hot Licks
    Commented Jul 2, 2020 at 21:26

3 Answers 3


The OED has a reference from 1873. I sense it may have been widely used in the two wars to describe soldiers and airmen who lost their nerve. The OED shows the abbreviation LMF meaning 'low moral fibre', which sounds like a file annotation for a personnel record.

moral fibre n. = moral courage n.; esp. in lack of moral fibre (abbreviated LMF).

1942 T. Rattigan Flare Path ii. ii. 140 And on my confidential report they'd put—grounded. Lack of moral fibre.


I am 80 years of age.Lack of moral fibre has been referred to over my life time and others that use the term ,as someone who is cowardly.I have no research to provide.Its a euphamism for cowardly,a softer terminology to not excite too much the person to which you are speaking.

  • @Xanne - "Lacks moral fibre" is a fairly common usage in the US. I take it to imply the person has poor "morals" and is apt to cheat/lie.
    – Hot Licks
    Commented Jul 3, 2020 at 3:25


a. Something that provides substance or texture.

b. Essential character: "stirred the deeper fibers of my nature" (Oscar Wilde).

c. Basic strength or toughness; fortitude: lacking in moral fiber.

Source: American Her. Dic.

It's use in a figurative sense has been common for a while. I think it refers to the threads that compose a texture, which in this case is likened to the morality of the character.

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