ill-

From Old Swedish ill- (“evil”). Attested since end of the 13th century. Related to illa.

ill-

1. evil

   ‎ill- + ‎vilja (“will”) → ‎illvilja (“ill-will”)

2. Generic amplifier

   ‎ill- + ‎grön (“green”) → ‎illgrön (“very green”)

   ‎ill- + ‎tjut (“shriek; howl”) → ‎illtjut (“loud shriek”)

• ill- in Svenska Akademiens ordlista (SAOL)
• ill- in Svensk ordbok (SO)