Aside from name (which is common amongst all), the Arabs also use title and agnomen. Among the Arabs, it was and still is a custom for an individual to have a name, title and agnomen.
Hazrat Mahdi (a.t.f.s.) possesses one special name: “ م ح م د ” Some believe that during his concealment, one should use his special name and a few say: ‘The prohibition of using his name goes back to the“short concealment period” when Hazrat feared he would be recognized. We have narrated the related tradition in our reply to another query.
Hazrat (a.t.f.s.) possesses various titles such as Mahdi, Hujjat, Qaem, Saheb-al-Zaman, Muntazer, Muntazar. A title is given after considering its meaning.
He has one ‘Kunya’ (agnomen) too. In the Arab culture, ‘Kunya’ is related to ‘Ab’ ( اب )”father” or ‘Umm’ ( ام )”mother”. In case of ladies, اُم appears before ‘kunya’ and in case of men, اَب is used. For example, they say: Abu-Zar- Abu-Abdullah- Abu’l-Qasi- Abu’l-Fazl and in case of women: Umm-Salma- Umm-ul-Baneen- Umm-Kulsum- Umm-Abiha. ‘Kunya’ does not necessarily require that for example a father should have a son named ‘Abdullah’ so that he can be given the ‘kunya’: Abu-Abdullah..
One of the Imam-e-Zaman’s titles is (Aba-Saleh)
ابا صالح It does not necessarily mean that he should possess a son named Saleh.
‘Abu-Saleh’ (or ‘Aba-Saleh’ or ‘Abi-Saleh’) means someone who possesses abundant goodness as if goodness is borne from him.
Thus, in case of children, ‘Kunya’ is used for two reasons: One reason may be in hope that they would have a child so that they are given that name. Another reason is that some outstanding qualities may be seen in him which is expressed in the form of ‘Kunya’. The one who distribute food among the poor is called ‘Abul-Qasim’; the one who helps is called ‘Abu-Hashim’ and an eatable that is refreshing and tasty (like falooda) is named ‘Abu-Sa’egh’ (Sa’egh means very refreshing).
One of Imam Husain’s (a.s.) ‘Kunya’ is“Abu-Abdullah” . It does not mean he should necessarily possess a son named Abdullah though he did possess one.“Abdullah” means Allah’s slave. It means he has reached the peak in serving Allah and he is the father of Allah’s slaves.
This was one matter about names, titles and agnomens. Hazrat Mahdi (a.t.f.s.) possesses many titles and agnomens because the holy prophet (s.a.w.a.), the Imams (a.s.) and Imam Hasan Askari (a.s.) [right from the time he gave glad-tiding about the existence of last Imam] have used various titles for him. The famous traditionist Haj Mirza Husain Nuri had narrated 182 names and titles for Hazrat Mahdi (a.t.f.s.).