Skittish is correct — it means easily frightened or nervous (a skittish horse, a skittish investor). Skiddish is a common ...

Both fuelled and fueled are correct. Fueled is the American spelling (one l). Fuelled is the British spelling (two l’s). ...

Shyer is correct and the most common comparative of shy. Shier is also correct but much less common — it ...

Saber means to know facts or how to do something — ‘Sé la respuesta’ (I know the answer), ‘Sé nadar’ ...

Focuses is correct and the most common spelling in modern English (both British and American). Focusses is also correct but ...

Ketchup is correct and the standard modern spelling for the tomato sauce. Catsup is an older variant spelling for the ...