The Iota-Chi Cross is formed by superimposing a letter I (Greek: Iota) on a letter X (Greek: Chi).
The explanation is sometimes simplified to be In Christo (In Christ) but the usual interpretation is that Iota is the first letter of Ιησουσ (Iesous: 'Jesus') and Chi is the first letter of Χριστοσ (Christos: 'Christ'). This I-X combination then becomes a cipher for Jesus Christ. (See also Chi-Rho Cross and other Christograms)
Having six 'arms', this cross is like a Snowflake and is sometimes confused with the similar looking Baptismal Cross.
In English, 'iota' means something 'incredibly tiny'. It comes from when the first uniform Christian doctrine (the Nicene Creed) was agreed way back in the 4th century.
Much of the debate centred around the nature of the Holy Trinity and whether Jesus was of the same substance as God the Father or only of similar substance. The Greek for the same substance is 'homoousios', whereas 'homoiousios' means similar substance. You will note the difference in spelling is just one tiny, but significant, letter; 'i' (Iota).
From this, we have English phrases such as: 'Not an iota of truth', 'Not one iota of doubt' etc., meaning not even a little bit.
Iota and Chi, along with other Greek letters, are used to form the names of several north American college fraternities, sororities, collegiate and alumnae chapters. Iota and Chi side-by-side give the Roman numeral IX, hence Iota-Chi could, for example, refer to the ninth chapter of a fraternity. (Iota happens to be the ninth letter of the Greek alphabet but has a value of eleven as a Greek numeral.)
Using one or more Greek letters implies such societies have passed the test of time. Whether the group has roots going back hundreds of years or is newly founded, the mere presence of Greek lettering gives immediate antiquity and respectability.
For the Iota-Chi Cross, however, no faking or imagination is required. The meaning behind the symbol is timeless, and just as relevant today as it was 2,000 years ago. (See the Meaning of the Cross)