Como fazer com que a verificação ortográfica do Vim se lembre de uma nova palavra

Estou usando o gvim para edição de látex. Escrevo muitos documentos científicos com palavras que o dicionário vim não conhece. Ao executar a verificação ortográfica, encontro palavras que eu sei que estão escritas corretamente, como adiciono essas palavras ao dicionário?

No manual do vim:

To add words to your own word list:

zg       Add word under the cursor as a good word to the first
         name in 'spellfile'.  A count may precede the command
         to indicate the entry in 'spellfile' to be used.  A
         count of two uses the second entry.

         In Visual mode the selected characters are added as a
         word (including white space!).
         When the cursor is on text that is marked as badly
         spelled then the marked text is used.
         Otherwise the word under the cursor, separated by
         non-word characters, is used.

         If the word is explicitly marked as bad word in
         another spell file the result is unpredictable.


zG       Like "zg" but add the word to the internal word list
         |internal-wordlist|.


zw       Like "zg" but mark the word as a wrong (bad) word.
         If the word already appears in 'spellfile' it is
         turned into a comment line.  See |spellfile-cleanup|
         for getting rid of those.


zW       Like "zw" but add the word to the internal word list
         |internal-wordlist|.

zuw
zug      Undo |zw| and |zg|, remove the word from the entry in
         'spellfile'.  Count used as with |zg|.

zuW
zuG      Undo |zW| and |zG|, remove the word from the internal
         word list.  Count used as with |zg|.

Na linha de comando:

:[count]spe[llgood] {word}
         Add {word} as a good word to 'spellfile', like with
         |zg|.  Without count the first name is used, with a
         count of two the second entry, etc.

:spe[llgood]! {word} Add {word} as a good word to the internal word list,
         like with |zG|.


:[count]spellw[rong] {word}
         Add {word} as a wrong (bad) word to 'spellfile', as
         with |zw|.  Without count the first name is used, with
         a count of two the second entry, etc.

:spellw[rong]! {word}   Add {word} as a wrong (bad) word to the internal word
         list, like with |zW|.

:[count]spellu[ndo] {word}
         Like |zuw|.  [count] used as with |:spellgood|.

:spellu[ndo]! {word} Like |zuW|.  [count] used as with |:spellgood|.

Para obter mais ajuda sobre ortografia no vim, digite :help spellou:help spell-quickstart