What is a Zionist is it a jewish person?

No. Zionism is a political philosophy.

Jewry is a culture... Some Jews are Zionists, some are anti-Zionists for certain reasons.

Some Gentiles are Zionists and some are anti-Zionists.

Is anti-Zionism anti-Semitic? No, they are unrelated; one is politics while the other is culture.

Some argue that Zionism is anti-Semitic.

From Jews Against Zionism...

Theodor Herzl (1860-1904), the founder of modern Zionism, recognized that anti-Semitism would further his cause, the creation of a separate state for Jews. To solve the Jewish Question, he maintained “we must, above all, make it an international political issue.”

Herzl wrote that Zionism offered the world a welcome “final solution of the Jewish question.” In his “Diaries”, page 19, Herzl stated “Anti-Semites will become our surest friends, anti-Semitic countries our allies.”

As far as Zionism is concerned, the founder of Zionism and apostate, Theodor Herzl, sought to intensify hatred of the Jew in order to enhance the cause of political Zionism. Here are some of his “pearls”:

“It is essential that the sufferings of Jews. . . become worse. . . this will assist in realization of our plans. . .I have an excellent idea. . . I shall induce anti-semites to liquidate Jewish wealth. . . The anti-semites will assist us thereby in that they will strengthen the persecution and oppression of Jews. The anti-semites shall be our best friends”. (From his Diary, Part I, pp. 16)