to become stronger or make something stronger [≠ weaken]:
feeling/belief/relationship[intransitive and transitive]
Our friendship has steadily strengthened over the years.
Steve's opposition only strengthened her resolve to go ahead.
strengthen something's ties/bonds/links etc
The university hopes to strengthen its ties with the local community.
The company plans to strengthen its hand (=make itself more powerful) in Europe by opening an office in Spain.
to make an organization, army etc more powerful, especially by increasing the number or quality of the people in it [≠ weaken]:
The team has been strengthened by the arrival of two new players.
if the financial situation of a country or company strengthens or is strengthened, it improves or is made to improve [≠ weaken]:
measures to strengthen the economy
to increase in value, or to increase the value of money [≠ weaken]:
money[intransitive and transitive]
The pound has strengthened against other currencies.
to make something such as your body or a building stronger [≠ weaken]:
Metal supports were added to strengthen the outer walls.
to help prove something:
Fresh evidence has greatly strengthened the case against him.
to increase in force:
The wind had strengthened during the night.