What is an antonym of steadily?

Here are some antonyms for "steadily," depending on the context:

For gradual, consistent increase/decrease:

* Erratically

* Fluctuatingly

* Unpredictably

* Sporadically

* Intermittently

* Suddenly

* Abruptly

For consistent, unwavering:

* Waveringly

* Hesitantly

* Uncertainly

* Irregularly

* Inconstantly

For calmly, without agitation:

* Restlessly

* Uneasily

* Fidgetingly

* Nervously

* Turbulently

For confidently, securely:

* Doubtfully

* Timidly

* Shakily

* Precariously

The best antonym will depend on the specific meaning of "steadily" in your sentence.