ふかfukaめるmeru
1.

To increase the depth of understanding or familiarity between individuals or concepts, enhancing emotional or intellectual connections.

2.

To gradually elevate the intensity or seriousness of a feeling or situation, fostering a more profound experience or awareness.

3.

To augment the extent or degree of an abstract quality, such as confidence or suspicion, often applied in contexts that involve development or progression rather than physical actions.

Example:

我々は親睦を深めた。