The concept behind absence is that there are obligations and duties implied, and the particular person in question is not living up to those duties, and the most obvious beginning point is a physical presence where those duties are being performed. At church, absence implies that each and every believer has a duty and obligation to be at church to participate in the activities there. The lack of attending is a basic “absence” which is a lack of physical presence, but the concept goes further, in that that person does not participate in the activities that take place there.

Doubting Thomas is a classic New Testament example, where the resurrected Christ appeared to the disciples, and Thomas was not there, and he missed out on the activities there. There is therefore a twofold thought, one of not identifying correctly because of a physical absence, and then there is the idea that a physical absence also including a missing out on blessings and on contributions that the person can or could of made to the activities at that church reunion.

-DCox

Merriam-Webster defines this as…

a state or condition in which something expected, wanted, or looked for is not present or does not exist : a state or condition in which something is absent.

a failure to be present at a usual or expected place

a period of time when someone is not present at a place, job, etc.

Absence.

• Missing, uncounted Eccl 1:15
• Purposeful separation John 14:28
• Feared reunion 2Co 12:20-21
• Believers reunited Phil 1:25-26
• Remembering those absent 1Th 2:17

[Anderson]