To make a tender of; to offer or tender.
"The dry leaves began to tend when a single spark from the campfire landed among them."
To look after (e.g. an ill person.)
To kindle; ignite; set on fire; light; inflame; burn.
In plain English: To tend means to take care of something or someone by doing what is needed for them to stay healthy or safe.
"My grandmother tends to her garden every morning."
Usage: Use this meaning only in formal legal contexts when referring to the official presentation of an insurance claim, lawsuit, or bid. In everyday speech and writing, avoid using it as a synonym for "tender" unless you are specifically discussing contractual offers.
The word "tend" comes from the Old French verb for stretching or holding something out. It entered English with this original sense of extending or offering before its meaning shifted to caring for someone or something.