This is the 12155th most frequent Russian word.
иммунолога
The Russian word "иммунолога" means "immunologist" in English (a specialist in immunology).
Here, 'иммунолога' is the direct object of the verb 'посетить', representing a professional specializing in immunology, whom the subject visited.
Прошлой неделей я наконец смог посетить иммунолога.
Last week I was finally able to visit the immunologist.
In this sentence, 'иммунолога' is used in the genitive case, specifying the type of professional whose consultation is needed.
Для точного диагноза потребуется консультация опытного иммунолога.
To obtain an accurate diagnosis, a consultation with an experienced immunologist is required.
Although the nominative form 'иммунолог' is used here, it illustrates the aspirations related to the profession.