| Answer | Crossword Clue |
|---|---|
| ARBOR | ... Day, first observed in 1872. |
| THANKSGIVING | National day of gratitude, first observed by the Pilgrims in 1621 |
| shive | a traditional seven-day period of mourning the dead that is observed in Jewish homes often used in the phrase sit shivah |
| yom | a Jewish holiday observed with fasting and prayer on the 10th day of Tishri in accordance with the rites described in Leviticus 16 called also Day of Atonement |
| POSITRON | Antiparticle first observed in 1929 |
| NEPTUNE | It was first observed in 1846 |
