Error: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $

I'm trying to consume data from an API using retrofit, however whenever I try to connect it returns that error. I'm using a class that is an Array of these objects (SisalfaCatalog) and throwing the return inside it, but it does not work. Here is the code:

The service interface:

public interface SisalfaService {

public static final String BASE_URL = "https://app.sisalfa.dcx.ufpb.br/v1/api/";

@GET("contexts")
Call<SisalfaCatalog> listPalavras();

}

The class with the Array of objects:

public class SisalfaCatalog {
public ArrayList<Palavra> palavras;

}

API Content:

[
{
    "id": 1,
    "name": "Sala",
    "image": "https://app.sisalfa.dcx.ufpb.br/v1/static/images/dababcd96ab5f7854f820ff926c9acaa.jpg",
    "sound": "",
    "video": "",
    "createdAt": "2018-06-22T19:31:18.745Z",
    "updatedAt": "2018-06-22T19:31:18.745Z",
    "user": {
        "id": 1,
        "username": "neto",
        "email": "[email protected]",
        "firstName": "José",
        "lastName": "Antonio da Silva Neto",
        "photo": null
    }
},

And the main with the service call:

        retrofit = new Retrofit.Builder()
            .baseUrl(SisalfaService.BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .build();


    SisalfaService service = retrofit.create(SisalfaService.class);
    Call<SisalfaCatalog> call = service.listPalavras();

    call.enqueue(new Callback<SisalfaCatalog>() {
        @Override
        public void onResponse(Call<SisalfaCatalog> call, Response<SisalfaCatalog> response) {
            if(!response.isSuccessful()) {
                Toast.makeText(MainActivity.this, "Errr, a conexão não deu certo", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(MainActivity.this, "Bem, deu certo aparentemente", Toast.LENGTH_LONG).show();
                SisalfaCatalog catalog =   response.body();

                for(Palavra p : catalog.palavras) {
                    Log.i("Nome: ", p.getName());
                    Log.i("Id: ", ""+p.getId());
                    Log.i("Url: ", p.getImage());

                }

            }

        }

        @Override
        public void onFailure(Call<SisalfaCatalog> call, Throwable t) {
            Toast.makeText(MainActivity.this, "Errr, não deu certo. "+t.getMessage(), Toast.LENGTH_LONG).show();
            Log.i("Erro: ", t.getMessage());
        }
    });