| Period prior to year zero, in dates | 35 |
| Period relative | 15 |
| Period sans soleil | 18 |
| Period since 1957 | 17 |
| Period sometimes named after a president | 40 |
| Period sometimes named for a statesman | 38 |
| Period spent at a particular job | 32 |
| Period starting about 1000 B.C. | 31 |
| Period starting on the second day of Passover | 45 |
| Period that appears endless | 27 |
| Period that ends Nov. 3rd, requiring a shift, and letters that shift in this puzzle's theme entries | 103 |
| Period that lasted around a millenium | 37 |
| Period that started with Sputnik | 32 |
| Period that unifies calendars | 29 |
| Period to find out more | 23 |
| Period to remember | 18 |
| Period to turn off one's phone and catch up on TV, say | 58 |
| Period to usher in | 18 |
| Period too long to measure | 26 |
| Period when a computer is functioning | 37 |
| Period when birds and mammals appeared | 38 |
| Period when Long Island was formed | 34 |
| Period when some buttercup-family plants are grown? | 51 |
| Period when things go poorly | 28 |
| Period with a name | 18 |
| Period with a tilde? | 20 |
| Period with limits | 18 |
| Period with little rainfall | 27 |
| Period with nothing to do | 25 |
| Period with overtime pay, perhaps | 33 |
| Period's place | 18 |
| Period's place in a sentence | 32 |
| Period, e.g. | 12 |
| Period, for one | 15 |
| Period, in a telegram | 21 |
| Period, in France | 17 |
| Period, in Paris | 16 |
| Period, in Web addresses | 24 |
| Period, say | 11 |
| Periodi-cal, for short | 22 |
| Periodic | 8 |
| Periodic "Top Chef" judge with a restaurant in Manhattan | 66 |
| Periodic activity of snakes | 27 |
| Periodic arrival that causes much angst | 39 |
| Periodic celebration | 20 |
| Periodic chart data: abbr. | 26 |
| Periodic dairy aisle offering | 29 |
| Periodic function | 17 |
| Periodic growth, as funds | 25 |
| Periodic Halloween sight? | 25 |
| Periodic income, in Paris | 25 |
| Periodic law figs. | 18 |
| Periodic maintenance | 20 |
| Periodic monster | 16 |
| Periodic obligations | 20 |
| Periodic oscillation | 20 |
| Periodic Pacific disruption | 27 |
| Periodic pay | 12 |
| Periodic payment | 16 |
| Periodic payments | 17 |
| Periodic produce outbreak | 25 |
| Periodic radio signal | 21 |
| Periodic record | 15 |
| Periodic review | 15 |
| Periodic riser | 14 |
| Periodic source of weird weather | 32 |
| Periodic table abbr. | 20 |
| Periodic table creator Mendeleev | 32 |
| Periodic table datum, briefly | 29 |
| Periodic table developer | 24 |
| Periodic table entry | 20 |
| Periodic table entry (Abbr.) | 28 |
| Periodic table fig. | 19 |
| Periodic table figs. | 20 |
| Periodic table info | 19 |
| Periodic table info: Abbr. | 26 |
| Periodic table items | 20 |
| Periodic table listing | 22 |
| Periodic table listings | 23 |
| Periodic table neighbor of cobalt | 33 |
| Periodic table neighbor of manganese | 36 |
| Periodic table no. | 18 |
| Periodic table period? | 22 |
| Periodic table stat | 19 |
| Periodic table stat. | 20 |
| Periodic table suffix | 21 |
| Periodic table's no. 10 | 27 |
| Periodic visitor | 16 |
| Periodic weather disruption | 27 |
| Periodic White House event | 26 |
| Periodic-table component | 24 |
| Periodic-table entries | 22 |
| Periodic-table item | 19 |
| Periodic-table listing | 22 |
| Periodic-table listing: Abbr. | 29 |
| Periodical | 10 |
| Periodical accessed by a URL | 28 |
| Periodical addendum | 19 |
| Periodical author | 17 |
| Periodical by and for enthusiasts | 33 |