While /u/malektewaus is correct that one of the more notable imagery of Crusades involve the Cross, it's more complex than just nailing two sticks together and waving it around. Peter Lock states that the term 'crusade' is a modern invention with its earliest use no later than 1638. Lock continues:

Muslim sources did not distinguish between western pilgrims, crusaders, or settlers, labelling them all as Franks (al-Franj). It is only in the twntieth century that the literal term for crusade, al-salibiyyun, enters Arabic historical writing. (Lock, 289)

To response to your question directly, crusade terminology from the 11th to 12th century was vague, fluid, and inconsistent. They were generally considered as pilgrimages or peregrinatio; its participants were peregrini. Other phrases used to describe a crusade include: passagium generale (general passage), expeditio crucis (expedition of the cross), and negotium Jhesu Christi (business of Jesus Christ). Bellum sacrum or Holy War was another favourite term. What it underscores is the variety of ways that letters described a crusade. Lock states that "the concept of crusade was not fully developed in the mind of [Pope] Urban II in 1095." By the mid-13th century, there is an increasing leaking of the vernacular language into crusade terminology: croiserie or croisement for 'crusade' and croize or croisse for 'crusader'. Then you have to define what is a crusade. I'll be borrowing from another post I made in regards to the Baltic Crusade.

Marek Tamm argues that the idea of crusade can be split into two camps - the purists and the pluralists. The purists, Tamm argues, view crusades by using the First Crusade as their model and the liberation of Jerusalem from non-Christian hands as their goal: as stated by Pope Urban II in 1095. It required the Pope to authorize it - to make it holy as a religious defensive war against the non-believer. All of its other aspects - penance, indulgence, pilgrimage, etc. were second to the goal of liberating Jerusalem and the Holy Lands from the Muslims. Those other 'holy wars' that did not have Jerusalem as its goal were deemed less than the 'True Crusade'.

In contrast, the pluralist, viewed the crusades as a movement that continuously evolved and emphasized its characteristics over its location. Lock states that a 'holy war' had to be religiously motivated, be authorized by the Pope, and "it must be a penitential pilgrimage preceded by taking the relevant pledge and (generally) also the taking of the cross, thereby offering the crusaders benefits in terms of salvation (Tamm, 434)."

Sources

The Routledge Companion to the Crusades - by Peter Lock

How to justify a crusade? The conquest of Livonia and new crusade rhetoric in the early thirteenth century - by Marek Tamm

There wasn't even a term in Muslim literature for the series of conflicts that we call the Crusades until Europeans introduced their understanding of this history to the Middle East in the early 1900s after the Ottoman Empire collapsed. From the Muslim perspective, the Crusades never captured a central place in history because they were a series of inconsequential failures on the part of the European forces -- everything lost to the Latin Kingdoms was won back in due course, so why treat these conflicts as special in a period characterized by heavy warfare within the Islamic world? It took colonial schools and European literature to introduce a different and more significant interpretation of these conflicts centuries later.

Source: Madden, Concise History of the Crusades

Follow up question - where did the name "crusade" come from?

According to the Catholic Encyclopedia, the term was derived from the iconic cross used to signify the vows crusaders took, and medieval writers used terms like crux, croiserie, etc., that are etymologically related to the term crusade. According to Jonathan Riley-Smith, in his book The First Crusade and the Idea of Crusading, the term cruce signati, "those marked with the cross", came into use to describe those who had taken the crusader's vow "almost immediately."