1. In a stern manner.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• storly,
• stanly,
• storngly,
• serrnly,
• sterly,
• starngly,
• stronly,
• sturnly,
• strenly,
• serinly,
• eternily,
• steaply,
• stely,
• stortly,
• steral,
• stearnly,
• sternley,
• steringly,
• sterny,
• sturnell

• strangled,
• string,
• straying,
• staring,
• sternpost,
• stroman,
• Stronach,
• sternal,
• Strine,
• stern,
• Strom,
• strange,
• Storino,
• Sternberg,
• styron,
• strum,
• Strahan,
• strongly,
• strunk,
• Stearns,
• staringly,
• stirringly,
• Sturm,
• sternness,
• sturman,
• Storing,
• storm,
• string up,
• strings,
• sternum,
• Strang,
• streamer,
• strangely,
• streng,
• strenuous,
• strangle,
• sterna,
• strongbox,
• strangling,
• stringency,
• sterne,
• styrene,
• stormy,
• strymon,
• sterninae,
• Sterner,
• Sternisha,
• sterns,
• stranded,
• stringer,
• stermer,
• strongman,
• Strawn,
• strength,
• strewn,
• strung,
• stormily,
• stringent,
• Stransky,
• strain,
• strangles,
• stringham,
• strangler,
• strong,
• strand,
• stringy,
• Stearn,
• strontium,
• stranger.

The adjective form of the word "sternly" is "stern".

The plural form of the word "sternly" is "sternlys". However, it is worth noting that "sternly" is an adverb and adverbs generally do not have plural forms.

The singular form of the word "sternly" is "stern"