Preventing a ligature

This is a strength of TeX: some pairs of letters are automatically replaced by a single glyph, for aesthetic reasons, as is done in letterpress. For example, when an f and an i are placed next to each other, the hood of the f would normally tend collide with the title of the i, which wouldn’t look very nice. TeX therefore replaces them with a new, prettier glyph: fi. This merging of glyphs is called a ligature.

The same mechanism is used to obtain the Spanish characters ¡ and ¿, which are typed in as !` and ?`.

In Cyrillic fonts used with OT2 encoding, the letter pair sh will produce the glyph ш (the sha letter).

But in some cases, one may want to prevent ligatures from occurring.

To prevent a single ligature, just separate the letters in the (La)TeX code with something that will produce nothing in the output file. For example: \/, {}, \mbox{}, \null. The T1 and OT1 font encodings also provide the \textcompwordmark command, which has the same purpose.

% With the automatic ligature:
offence

% Without it:
of\/fence
of{}fence
of\null fence
of\mbox{}fence
of\textcompwordmark fence

Note that, in some cases, {} seems to have no effect, and the ligature occurs in spite of it. This is apparently a side effect of some packages, such as multicol. The other solutions may therefore be preferred. In all cases, hyphenation of the word is no longer performed automatically by TeX, and you have to take care of it manually, if needed.

The same solution prevents kerning between consecutive characters. Compare for example the rendering of AV and A\/V.

In case you want to prevent ligature in you whole document, have a look at fontspec options. It can disable all aesthetic ligatures, or disable them on a type by type basis:

\usepackage{fontspec}
 
\defaultfontfeatures{
  Ligatures={
    NoCommon,
    NoRequired,
    NoContextual,
    NoHistoric,
    NoDiscretionary
  }
}

FAQ ID: Q-prevlig
Last updated: 2021-04-18